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Al-Tamimi, J. 2017 Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic: Implications for formal representations.
Laboratory Phonology: Journal of the Association for Laboratory Phonology
8(1): 28, pp. 1–40, DOI: https://doi.org/10.5334/labphon.19
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phon
Journal of the Association for
Laboratory Phonology
Laboratory Phonology
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JOURNAL ARTICLE
Revisiting acoustic correlates of pharyngealization
in Jordanian and Moroccan Arabic: Implications for
formal representations
Jalal Al-Tamimi
Speech and Language Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
Jalal.Al-Tamimi@newcastle.ac.uk
This exploratory study of Jordanian and Moroccan Arabic (JA and MA) aims to evaluate whether
pharyngealization is associated with an epilaryngeal constriction which causes ‘retraction’
and tense voice quality in surrounding vowels, following the Laryngeal Articulator Model (LAM)
(Esling, 2005). Twenty male speakers (10 per dialect) produced vowels preceded by /d or d/.
Thirteen acoustic correlates obtained at the onset and midpoint were used to assess this type of
constriction. A predictive modeling approach was used; starting with Bayesian Generalized Linear
Mixed Effects modeling followed by Conditional Random Forest for classification. Vowels in the
pharyngealized context were more open (higher F1, Z1-Z0), more back (lower F2, higher Z3-Z2),
more compact (lower Z2-Z1), and showed spectral divergence (higher Z3-Z2). Voice quality results
showed these vowels to be produced with a tense voice. High classification rates of 93.5% for JA
and 91.1% for MA were obtained and variable importance score showed formant-based measures
outperform voice quality ones. This suggests pharyngealization has ‘retraction,’ with a back and
down gesture, as a primary correlate followed by [+ ]. The implications of
these results provide strong support for LAM, the feature [+], and the use of the epilarynx to
describe pharyngealization.
Keywords: acoustics of pharyngealization; tense/pressed voice; constricted epilarynx; Bayesian
GLMM; Random Forests; Jordanian and Moroccan Arabic
1 Introduction
Pharyngealization (or emphasis) in Arabic is generally assumed to involve retraction of
the tongue dorsum towards the upper pharyngeal area, which leads to a lowering of the
second formant in the surrounding vowels (e.g., Bin-Muqbil, 2006; Ghazeli, 1977; Watson,
2007; Zawaydeh, 1999; Zawaydeh & de Jong, 2011). Although these characteristics are
mostly agreed upon, pharyngealization is also associated with a retracted epiglottis, a
raised larynx, a pressed/tense voice quality, and/or a protruded lip posture (see e.g.,
Al-Tamimi, F. & Heselwood, 2011; Cantineau, 1960; Hess, 1998; Laufer & Baer, 1988;
Lehn, 1963; Zeroual & Clements, 2015; Zeroual et al., 2011, among others). Although
located near the constriction observed for ‘true’ pharyngeals, authors claimed that the two,
i.e., ‘true’ pharyngeals and pharyngealization, share the same place but vary in degree of
constriction (e.g., Laufer & Baer, 1988). Hence, and following the Laryngeal Articulator
Model (Esling, 2005), both will share an epilaryngeal constriction that may be exhibited
back and down in a one combined gesture and causes the vowels to be produced with the
‘retracted’ quality (Esling, 2005; Moisik, 2013a; Sylak-Glassman, 2014a, b). A secondary
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic
Art. 28, page 2 of 40
consequence of an epilaryngeal constriction causes a change in the voice source with an
increase in harmonic amplitude especially in high frequencies (Halle & Stevens, 1969;
Laver, 1980; Moisik, 2013b; Moisik & Esling, 2010; Stevens, 1977, 1998; Story, 2016).
This increase is generally associated with a tense/creaky/harsh voice quality (Edmondson
& Esling, 2006; Kuang & Keating, 2012, 2014; Moisik, 2013b). Our aim in this study is to
provide a complete analysis of the acoustics of Arabic pharyngealized plosives in order
to evaluate the presence of acoustic evidence for epilaryngeal constriction. In addition to
metrics as an alternative correlate to the articulatory ‘retracted’ vowel quality that is
associated with an epilaryngeal constriction (Esling, 2005). Acoustic correlates of voice
voice quality as a consequence of an epilaryngeal constriction.
The paper is organized as follows. The sections following this introduction provide an
overview of the literature on the phonetics of pharyngealization, with special attention on
the consequences of epilaryngeal constrictions, before outlining the goals of the current
study. Section 2 presents the method used in this study including speakers, dialects, and
the corpus from which they were drawn, as well as the acoustic analyses and statistical
design. Section 3 presents the results, starting with the most typically used acoustic
and acoustic correlates of voice quality. Finally, this section presents an exploratory
both dialects. The last section ends with a discussion of the results and their implications
for the current descriptions of pharyngealization. It is hoped that these accounts will open
the door to further research into the role of the laryngeal activity that is associated with
pharyngealization and pharyngeals in general.
1.1 Correlates of pharyngealization
Pharyngealization is a secondary articulation that involves a constriction located in the
pharyngeal area that causes retraction of the body and root of the tongue towards the
linguo-pharyngeal whereby the root of the tongue, including the epiglottis, moves backwards
to narrow the pharynx in the front-back dimension. In many, if not all, languages, a
narrowing of the pharyngeal passage near the tip of the epiglottis, and a raised larynx are
the direct consequences of this constriction (see e.g., Catford, 1977, p. 193; Ladefoged
& Maddieson, 1996, p. 307). Although this secondary articulation is pertinent to vowels
(Ladefoged & Maddieson, 1996, p. 306), in Arabic and many Semitic languages, however,
(Laver, 1994).
In Arabic, pharyngealization is associated with consonants that have a primary
muṭbaqa
mustaliya mufaḫḫama
(Bin-Muqbil, 2006; Cantineau, 1960; Jakobson, 1957/1962; Khattab et al., 2006; Lehn,
muṭbaqa
which describes their articulation as being ‘covered’ or ‘lidded’ (Khattab et al., 2006);
‘spread and with a raised tongue’ (Lehn, 1963) and/or with a ‘pressed voice’ (Cantineau,
1960, p. 23). The second term, mustaliya
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic Art. 28, page 3 of 40
grammarians as consonants with a ‘pressed voice’ while the others are not (Cantineau, 1960,
pg. 23–24). The last term used by Arab grammarians is mufaḫḫama
‘thick, heavy’ consonants, which describes all the consonants with an ‘emphatic’ acoustic
impression that seem to block Imāla
articulation, expressed as ‘pressed voice,’ as they were described separately from other
consonants that may share some of their articulatory features. As will be seen in the next
section, none of the studies reported below have attempted to explore the nature of this
‘pressed voice’ quality, hence our aim is to evaluate its acoustic consequences.
1.1.1 Articulatory-acoustic correlates
Based on perturbation theory and the acoustic theory of speech production (Carré &
Johnson, 2012; Mrayati et al., 1988; Stevens, 1989), articulatory to acoustic mapping
can be used to evaluate the acoustic consequences of constriction location. A pharyngeal
constriction causes a combined high F1 and low F2 due to the constriction being close
to a node for F1 and an antinode for F2, leading to respectively a rising and a lowering
of their natural frequencies. This correlates well with the quantal region located in the
pharynx (Stevens, 1989). When a pharyngeal constriction is associated with roundness/
lip protrusion, as correlates of pharyngealization in general, one would expect a closer
proximity between F1 and F2 and a lower F3. This is especially pertinent for front vowels
(Fant, 1960/1971; Lindblom & Sundberg, 1971; Stevens, 1989; Wood, 1986). Back vowels
with the back cavity; an increased constriction in the pharynx leads to an increase in
the length of the front cavity, and subsequently an increase in F3 (Stevens, 1989). This
increase in F3 can be caused by either a narrower constriction in the upper pharynx
constriction (Stevens & Keyser, 1989, p. 101) or due to a tighter tongue constriction in the
pharyngealized context (see e.g., Fant, 2004, p. 43; Lindblom & Sundberg, 1971, p. 1175).
These predicted consequences are evaluated empirically. The exact location of the
constriction responsible for producing pharyngealization in Arabic varies from a (post-)
velar to a (mid-)low pharyngeal (Khattab et al., 2006). Many researchers estimate this
constriction to be located towards the posterior pharyngeal wall in the vicinity of the upper
pharynx near the uvula and designate it only with tongue dorsum retraction (e.g., Bin-
Muqbil, 2006; Ghazeli, 1977; Hassan & Esling, 2011; Zawaydeh, 1999; Zawaydeh & de Jong,
2011). This retraction causes lowering of the second formant in the vowels surrounding
pharyngealized consonants and this is believed to be the main acoustic correlate to the
contrast (e.g., Al-Ani, 1970; Al-Masri & Jongman, 2004; Al-Tamimi, F. & Heselwood,
2011; Al-Tamimi, J. & Barkat-Defradas, 2003; Barkat-Defradas et al., 2003; Ghazeli, 1977;
Jongman et al., 2011; Khattab et al., 2006; Laufer & Baer, 1988; Obrecht, 1968; Shahin,
1996, 1997; Zawaydeh, 1999; Zawaydeh & de Jong, 2011; Zeroual et al., 2011, inter
alia). Given the ‘pharyngeal’ component of pharyngealization, a few studies reported a
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic
Art. 28, page 4 of 40
Heselwood, 2011; Al-Tamimi, J. & Barkat-Defradas, 2003; Barkat-Defradas et al., 2003;
Ghazeli, 1977; Jongman et al., 2011; Khattab et al., 2006; Laufer & Baer, 1988; Shahin,
for F2, and this led many researchers to consider only F2 as the main acoustic correlate
to pharyngealization in Arabic (e.g., McCarthy, 1994; Watson, 2007). The frequency of
the third formant (F3) was reported to be overall higher in the pharyngealized context
and sometimes dependent on the vowel quality; a higher F3 was reported with back
by the slight lip-rounding/protrusion and/or sulcalization of the tongue body reported in
the literature (Khattab et al., 2006).
Given the proximity between F1 and F2 observed in ‘true’ pharyngeals and
pharyngealization, it was used as an acoustic correlate of the auditory impression of
‘darkness’ or ‘heaviness’ reported in the literature, with pharyngeals obtaining Z2-Z1
(or F2-F1 in Bark) distance below the 3.5 Z threshold for formant merging, whereas
pharyngealized consonants were slightly above this threshold (close to 4.5 Z) (e.g.,
Al-Tamimi, F. & Heselwood, 2011; Heselwood & Al-Tamimi, F., 2011). This proximity
correlate to the separation between pharyngealized and non-pharyngealized consonants
in Arabic, either at the midpoint in Jordanian and Moroccan Arabic (Al-Tamimi, J., 2002;
Al-Tamimi, J. & Barkat-Defradas, 2003; Barkat-Defradas et al., 2003) or at the onset in
Moroccan Arabic (Yeou, 2001). We will be using this (and other) formant proximity
measures as correlates of pharyngealization.
investigated the acoustic and perceptual correlates responsible for distinguishing between
uvular and pharyngeal consonants. At the onset of the vowel, pharyngeals were associated
with a higher F1 and lower F2 frequencies, an increased bandwidth of the F2 (through
an estimated A2-H1 value), and a smaller distance between F2-F1, whereas uvulars had
a relatively stable F1 and slight raising of F2, a larger distance between F2-F1 and an
increased bandwidth of F1 (through an estimated A1-H1 value). These same results were
separation between pharyngeals and uvulars and thus we will be using it as a potential
correlate for pharyngealization.
1.1.2 Epiglotto-laryngeal articulation
Although it is assumed that pharyngealization is accompanied by retraction of the
tongue body, a few studies reported a constriction much lower in the vowel tract. Using
various articulatory techniques, researchers have shown pharyngealized consonants to
be produced with the epiglottis forming a constriction with the pharyngeal wall in the
vicinity of the middle or lower pharynx that is also accompanied by tongue root/epiglottis
retraction and larynx raising (e.g., Al-Tamimi, F. & Heselwood, 2011; Laufer & Baer,
1988; Zeroual & Clements, 2015; Zeroual et al., 2011). It is not clear then whether
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic Art. 28, page 5 of 40
pharyngealized consonants in Arabic have tongue root retraction and larynx raising that
leads to a tense/pressed voice quality. In her comparative study of tongue root activity in
various languages including Arabic using factor analyses of Ghazeli’s (1977) x-ray data,
Hess (1998) showed that the pharyngealized set in Arabic is better characterized by an
upper pharyngeal constriction. However, her results showed that the pharyngealized set
(both consonants and surrounding vowels) is also accompanied by tongue root retraction
(through the Laryngopharyngeal Constriction Factor), partial constriction at the pocket of
the epiglottis (through the Radical Constriction Factor), raising of the larynx, and widening
of the pharyngeal wall (through the Pharynx Shifting Factor) (Hess, 1998, p. 233). In fact,
explained that in addition to the “slight retraction, lateral spreading, and concavity of the
tongue and raising of its back (what has been called velarization),” emphatic consonants
are associated with “faucal and pharyngeal constriction (pharyngealization),” “slight lip
protrusion or rounding (labialization),” and/or “increased tension of the entire oral and
pharyngeal musculature resulting in the emphatics being noticeably more fortis than the
plain segments.”
More recently, the same patterns of tongue root/epiglottis retraction and larynx raising
of pharyngealized consonants were observed by Al-Tamimi, F. and Heselwood (2011)
acoustic data and by Zeroual et al. (2011) and Zeroual and Clements (2015) on 2–3
speakers of Moroccan Arabic using nasoendoscopic, ultrasound, EMA, and acoustic data.
and pharyngealized consonants while examining emphasis spread in the productions of 1
pharyngeal consonants showed aryepiglottic sphinctering, tongue root retraction, and
larynx raising as a direct consequence of a laryngeal constriction, while pharyngealized
consonants only showed tongue body retraction and raising accompanied by larynx lowering.
these discrepancies. Another possibility is related to the fact that the pharyngealized set
is produced with retraction of the tongue dorsum and/or root, whereas pharyngeal sets
have a retraction of the tongue root as an enhancement of the epilaryngeal constriction
Moisik, 2013a; Sylak-Glassman, 2014b). A slight larynx raising and/or constriction in the
pharyngealized vowels and consonants in Arabic compared to pharyngeals may still be
degree of larynx raising and/or constriction in pharyngeal and pharyngealized sets is an
important point to investigate further both articulatorily and acoustically in order to shed
light to the exact nature of the production of these consonants.
Table 1 provides a summary of the main articulatory and acoustics correlates as observed
in the literature, with the additional acoustic correlates as investigated in this study. It
aims at providing a correlation between articulatory and acoustic correlates in order to
highlight the missing acoustic correlates of the laryngeal activity.
show that its articulatory correlates form a complex picture with retraction of part(s) of
the tongue (dorsum and/or root), retraction of the epiglottis, raising and/or constriction of
the larynx leading to a more tense or pressed voice quality, and lip rounding/protrusion.
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic
Art. 28, page 6 of 40
there do not seem to be any accounts of the acoustic correlates of the tense or pressed
articulation, and/or raised larynx, which are usually measured in terms of articulation
(although see our own research Al-Tamimi, J., 2014, 2015). The next section introduces
more in-depth account of the consequences of an epilaryngeal constriction following the
Laryngeal Articulator Model.
1.2 Epilaryngeal constriction
Both classic and more recent articulatory reports of pharyngealization and ‘true’
pharyngeals sharing the same constriction location lead to the conclusion that articulatorily
speaking, pharyngealization in Arabic is produced by constricting the epilaryngeal tube.
This, in turn, has a direct consequence on retracting the tongue body due to tongue
root retraction, with a concomitant larynx raising and/or constriction. This is the view
developed in the Laryngeal Articulator Model on the type of constriction seen in the
epilarynx (Esling, 2005). This model was extensively modeled by Moisik (2013a) and
typologically and formally evaluated in Sylak-Glassman (2014a). According to Moisik
(2013a, p. 84), the lower vocal tract “is bounded inferiorly by the glottis and superiorly
by the oropharyngeal isthmus and velo-pharyngeal port.” The epilarynx is located within
the lower vocal tract above the larynx and has the ventricular folds as its lower part and
the rim formed by the epiglottis and aryepiglottic folds as its upper part (Moisik et al.,
2012). Pharyngeals in general (and potentially pharyngealized consonants in particular)
are produced by sphincterally constricting the epilarynx through constricting the
intrinsic or the extrinsic laryngeal muscles (Esling, 2005; Moisik, 2013a; Sylak-Glassman,
2014a, b); tongue retraction is caused by this constriction and is seen as a facilitator and
an enhancer of the pharyngeal articulation (Esling, 2005; Moisik, 2013a; Sylak-Glassman,
2014a, b). Constriction of the hyoglossus muscle draws the tongue as a whole backward
and downward and leads to retraction of the tongue root and dorsum (Moisik, 2013a,
‘retracted’; they are produced by a back and down gesture, which partially matches the
consequences we see with pharyngealization.
The constriction as seen in the laryngeal area, and particularly in the epilarynx, has
direct consequences on the quality of the sounds produced; ventricular folds couple with
the vocal folds and are brought down to the glottis to allow for creaky phonation to occur
(Moisik, 2013a; Sylak-Glassman, 2014a, b) and when constricted they are associated with
laryngealization, tense and harsh voice quality (Edmondson & Esling, 2006; Stevens,
1977). Aryepiglottic fold constriction is associated with an enhanced and clearer voice
quality especially in singing due to an increased energy in the higher frequencies as well as
Table 1: List of articulatory and acoustic correlates of the effects of pharyngealization on the
surrounding vowels as highlighted in the literature and the supplementary correlates used in
the current study.
Articulatory Acoustic Additional correlates
Retraction ⇓ F2 ⇑ F3-F2
Open ⇑ F1 ⇑ F1-F0
Narrow/compact ⇓ F2-F1, ⇓ F3 ⇓/⇑ F3-F2
Roundness/lip-protrusion ⇓ F1 & F2 & F3 ⇓ F2-F1, ⇓/⇑ F3-F2
Raised larynx ⇑ F1, ⇓ F2 & F3 Spectral slope
Pressed/tense voice – Spectral slope
Epilaryngeal Constriction – Amplitude upper harmonics
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic Art. 28, page 7 of 40
fold constriction is observed in the production of ‘true’ pharyngeal consonants (Esling,
2005) and a few studies reported ‘trilling’ as a direct consequence of ‘true’ pharyngeal
and pharyngealization; the former is produced by constricting the aryepiglottic folds as
a primary feature whereas the latter by constricting the ventricular folds as a secondary
feature. Pharyngeals were described as having tongue root retraction and lowering,
epiglottal retraction, in addition to larynx raising as one component (Esling, 2005;
Hassan & Esling, 2011; Moisik, 2013a)—descriptions that seem to match the few reports
of pharyngealization in Arabic (see Section 1.1.2). This seems to suggest that the whole
guttural class, including pharyngeal, pharyngealized, and uvular consonants, is produced
with an epilaryngeal constriction, albeit to varying degrees of stricture and phonation
(Moisik, 2013a; Sylak-Glassman, 2014a, b).
1.2.1 Acoustic consequences
From an acoustic point of view, and given that the vowels in the vicinity of pharyngealized
consonants are better described as ‘retracted’ (Sylak-Glassman, 2014a, b), we will
advocate the use of the proximity between formants as an (psycho-)acoustic correlate.
perception, and normalization (e.g., Syrdal & Gopal, 1986; Thomas & Kendall, 2007,
inter alia). The proximity between Z1-Z0 (that is F1-f0 in Bark) correlates well with the
openness dimension (i.e., [±
& Gopal, 1986; Traunmüller, 1981), with more close ([+
lower than 3 Bark, and more open ([–
p. 1090). Z2-Z1 correlates well with compactness of the specturm (Sylak, 2011; Syrdal
& Gopal, 1986) and is highest for front vowels, and lowest for (mid-)open back vowels
open back and back vowels and the smallest for front vowels and correlates well with
the backness/retraction of vowels (Syrdal & Gopal, 1986, p. 1090). Z3-Z2 correlates well
/i/ to distinguish it from /y/ (Wood, 1986). Thus we also hypothesize that a large Z3-Z2
formant merging observed in Z2-Z1 due to the pharyngeal constriction. Hence we expect
the vowels in the vicinity of pharyngealized consonants to show a higher Z1-Z0, a lower
Z2-Z1, and a higher Z3-Z2.
Voice source changes occur with an epilaryngeal constriction. Constricting the
ventricular folds leads to a tense, pressed, or laryngealized voice quality with an overall
& Stevens, 1969; Hanson et al., 2001; Klatt & Klatt, 1990; Laver, 1980, 1994; Moisik,
2013b; Moisik & Esling, 2010; Stevens, 1977, 1998; Sundberg & Askenfelt, 1981). When
an epilaryngeal constriction is caused by an aryepiglottic fold constriction an ‘enhanced’
voice quality, especially in singing, can be seen (Moisik & Esling, 2010; Story, 2016;
Titze, 2008; Titze & Story, 1997). Samlan and Kreiman (2014) described the acoustic and
perceptual consequences of constricting the epilarynx at either the aryepiglottic or the
constrictions. We will be investigating spectral slope measures that are widely used as an
acoustic evaluation of phonation and voice qualities which have been successfully used to
distinguish non-modal from modal phonation (e.g., Garellek, 2012; Hanson et al., 2001;
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic
Art. 28, page 8 of 40
Keating et al., 2015; Klatt & Klatt, 1990; Kuang & Keating, 2012; Ladefoged & Maddieson,
1996, among others).
f0,
2*f0, F1, F2, and F3 and are expressed as H1, H2, A1, A2, and A3 respectively. Garellek
(2012) and Kuang and Keating (2012) provide a comprehensive summary of the various
acoustic correlates of phonation and spectral slope. Given that the tense/pressed voice
quality was reported in the context of pharyngealization, we will restrict the explanations
below to the creaky/tense/pressed voice quality correlates as compared to breathy voice
quality. A tense/pressed voice tends to show a lower H1-H2 as the main acoustic correlate
(e.g., Garellek, 2012; Hanson et al., 2001; Keating et al., 2015; Klatt & Klatt, 1990; Kuang
& Keating, 2012; Ladefoged & Maddieson, 1996, among others). Spectral tilt measures,
i.e., H1-A1, H1-A2, and H1-A3 seem to be directly correlated with the abruptness of
vocal fold closure (Garellek, 2012; Hanson et al., 2001). H1-A1 correlates well with the
bandwidth of F1; as the bandwidth of F1 increases, the amplitude of the harmonic closest
to F1 decreases and thus a lower H1-A1 indicates a creaky/tense voice (Garellek, 2012;
Hanson et al., 2001; Kuang & Keating, 2012). H1-A2 and H1-A3 are also correlated with
creaky/tense phonation, showing lower values (Garellek, 2012; Klatt & Klatt, 1990; Kuang
& Keating, 2012). Hanson & Chuang (1999) and Hanson et al. (2001) described how an
abrupt closure of the glottis can yield a change in the source spectrum; a decrease in
spectral tilt around F3 is observed, and hence a lowered H1-A3 would be expected. If the
folds, then an increase in spectral tilt would be seen and a higher H1-A3 is obtained. This
should not be seen as an indication of an increased noise, as an increased noise as seen in
breathy voice and/or glottal opening will increase spectral tilt further and H1-A3 will be
much higher (for more detail, see e.g., Hanson & Chuang, 1999; Hanson et al., 2001; Klatt
A1-A2 is directly related to phonation types, and thus a creaky/tense voice tends to have
lower A1-A2 (Aralova et al., 2011; Fulop et al., 1998; Guion et al., 2004; Kang & Ko,
tongue root leads to an increase in the energy of the harmonics above F1. This increase
can either be extensive in that the energy in A2 and A3 are higher than that of A1;
consequences of an extreme epilaryngeal constriction that leads to an ‘enhanced’ voice
(Story, 2016). In this case, a lowered or even negative A1-A3 and A2-A3 is obtained due to
the concentration of energy around F3, F4, and F5 as seen in the ‘singer’s’ formant (Story,
2016). However, when the epilaryngeal constriction is minimal and/or is associated with
a primary pharyngeal constriction, we would expect a change in the pattens. This would
A1-A3 and A2-A3, due to the decrease in
energy around F3. This again correlates well with the acoustic consequences of an abrupt
closure of the vocal folds (Hanson et al., 2001).
1.2.2 Formal representation
As we saw above, an epilaryngeal constriction yields both a ‘lingual’ and a ‘laryngeal’
shift from considering lingual or laryngeal constrictions separately and can be used to
describe the post-velars as one set of combined articulations (for more detail on the
glottocentric vs linguocentric view, see Moisik, 2013a; Moisik et al., 2012; Moisik & Esling,
2011; Sylak-Glassman, 2014a, b). This allowed for the introduction of a new set of
[±
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic Art. 28, page 9 of 40
Lower-Vocal-Tract Phonological Potentials (Moisik, 2013a), [+
sounds to be retracted, constricted and to have raised larynx voice and tense phonation;
all as a combined unit (Moisik, 2013a; Moisik et al., 2012; Moisik & Esling, 2011).
‘Retracted’ is due to tongue and epiglottis retraction with a back and down gesture;
‘constricted’ of certain intralaryngeal muscles and ‘raised larynx’ leading to tense voice
quality (Moisik et al., 2012, p. 5). The feature [+
pharyngeals/epiglottal and pharyngealized/epiglottalized categories with the former
being assigned this feature as a primary place feature, whereas the latter receives it as a
secondary feature (Sylak-Glassman, 2014a, p. 136–138). Following Moisik et al. (2012)
and Moisik and Esling (2011), ‘true’ pharyngeals (and other categories) are assigned
this feature as an indication of the primary constriction of the epilarynx; pharyngealized
consonants are assigned [+
p. 138). Whether all or parts of these combined articulatory consequences are to be used
depends on the category of sounds (Moisik et al., 2012, p. 5–6), hence pharyngealized
consonants may show tongue root retraction and/or intralaryngeal muscle constriction
but not larynx raising, etc. (for more detail, see e.g., Moisik & Esling, 2011, table 2,
p. 1407 on pharyngeal and pharyngealized categories being producing by a glottal source,
yielding a raised larynx and a [+
where pharyngeal and pharyngealized receive a [+
1.3 Aims of the current study
This exploratory study aims at acoustically investigating whether an epilaryngeal
constriction is associated with pharyngealization in Arabic. We take the views developed
in the Laryngeal Articulator Model that an epilaryngeal constriction leads to a ‘retracted’
vowel in the pharyngeal area with both tongue backing and lowering that causes a
tense/pressed/laryngealized voice quality due to constricting the larynx. Acoustically
speaking, we expect the vowels in the pharyngealized context to show a raised F1 and
Laryngeal Articulator Model, as well as a raised Z3-Z2 signaling both backness and spectral
divergence as an enhancing correlate to the already lowered Z2-Z1. F3 can potentially
show a lowered value if pharyngealization is produced in the mid-low pharynx for front
vowels or a raised F3 for back vowels due to the tighter constriction. Spectral slope and
voice quality correlates are expected to correlate well with the tense/pressed voice quality
with an overall lowered H1-H2, H1-A1, H1-A2, H1-A3, A1-A2, and with an increased
lowered A1-A3 and A2-A3.
2 Method
2.1 Material
2.1.1 Speakers
Twenty Jordanian and Moroccan male speakers (10 of each dialect), aged 20 to 30,
participated in this experiment. Jordanian Arabic speakers originated from Irbid in
the north of Jordan whereas Moroccan Arabic speakers come from Mohammedia (near
Casablanca). They all reported no history of articulatory or hearing disorders, and shared
university, and all lived in the city (i.e., spoke an urban variety). Some Jordanian Arabic
speakers had some knowledge of French and/or English (beginner to advanced levels),
while Moroccan Arabic speakers were non-Berber, and had knowledge of French. Both
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2.1.2 Dialects
Although Jordanian and Moroccan are dialects of the same language, some important
They belong to the eastern and western zones respectively, and some researchers have
Vowel inventories are reduced in western dialects compared to the eastern ones (Marçais,
(Al-Tamimi, J., 2007a; Al-Tamimi, J. & Ferragne, 2005; Barkat, 2000). A more complex
syllable structure seems to operate in western dialects (Cohen, 1962), which has a direct
(or more halting) rhythmic structure than eastern dialects (Barkat, 2000; Ghazali et al.,
in placement of stress, although their patterns in producing the statements that are used
the two zones are important enough for the dialects to be mutually unintelligible, which
A key aspect of the current study is to evaluate whether the phonetic implementation
perspective, Bellem (2007) suggested that pharyngealization is implemented in the same
manner, although some dialects can show more of a ‘guttural’ quality than others. It is
not clear however, what is meant by a more ‘guttural,’ whether it is more mid-to-low
of pharyngealization with Moroccan Arabic speakers having the mostly distinctive locus
equation slopes, followed by Jordanians (and then the two other dialects, Kuwaiti and
steeper formant slopes of F1, F2, and F3 were obtained in JA (Al-Tamimi, J., 2007a, b).
between these two dialects in how pharyngealization is implemented.
2.1.3 Material and recordings
The material used in this exploratory study comes from a larger corpus on bilabial, alveolar,
and velar stops that was used to investigate the role of dynamic correlates (i.e., formant
slopes) in production and perception (for more details, see Al-Tamimi, J., 2007a, b). The
real words used in this study are listed in Table 2. Voiced alveolar pharyngealized and
1V11V11V1CVC, or
1V1C syllable structures, where C1 =1 =
used, it was not possible to obtain minimal sets for the two varieties nor comparable
sometimes either in initial or medial positions, or with other ‘guttural’ sounds present
with cross-dialectal variations, emphasis spread is greater from coronal pharyngealized
consonants, i.e., ‘true’ emphatics compared to other ‘guttural’ sounds (Hellmuth, 2013;
Watson, 2007). In addition, rightward emphasis spread is more common than leftward
(Hellmuth, 2013), although Bellem (2007) seems to suggest small variations between
dialects in how this aspect is implemented. Given these restrictions, our aim is to evaluate
how these additional acoustic correlates can be used on such a corpus.
The speakers were seated in front of a computer in a sound attenuated room (for
Jordanian Arabic speakers) or in a very quiet room (for Moroccan Arabic speakers), and
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for this task. After a training phase, and for purposes of other experiments using this
dataset, speakers were asked to produce each item as realized in the target word, in
the target CV syllable and then in the target isolated vowel, while trying to keep the
production of each vowel constant across realizations and having at least 0.5 sec gap
between each sequence. This particular task is aimed at evaluating the role of contextual
information on the degree of vowel hypo- vs hyper-articulation and in vowel perception
(for more details see Al-Tamimi, J., 2007a). The words were randomly presented with
and to obtain the real dialectal realization of each word. The carrier sentence had an
important role here as it was used as a way to convey the meaning of the unvocalized
some speakers produced a non-dialectal form; in these cases, the experimenter clicked
speaker was asked to reproduce it. In this second round of production, most speakers
reproduced the words in a dialectal form. The quality of the productions was assessed
by the author and in the case of Moroccan Arabic by a native speaker of the variety.
Speakers were asked to produce each word, while not moving or modifying the distance
then digitized directly on the same computer, with a sampling frequency of 22.05 kHz,
16-bit quantization, in mono channel using a Sony MS 907 microphone (distance 15–20
cm from the speakers’ mouths). Given that the corpus used here is part of a larger study
vowels, the length of all the experiments (production and perception) was about 2 hours
per speaker (for more details see Al-Tamimi, J., 2007a). For the current study, vowels
realizations as a function of the pharyngealized vs non-pharyngealized environments;
the total number of words produced by the speakers for this study was 700 for Jordanian
and 500 for Moroccan Arabic (henceforth JA and MA).
2.2 Data processing and acoustic analyses
Table 2: List of items used in the current study for both JA and MA.
/iː/ /ɪ/ /eː/ /aː/ /ɐ/ /ʊ/ /uː/
JA
/d/ ˈdiːnak ˈdɪjja ˈdeːr ˈdaːr ˈdɐm ˈdʊbb ˈduːd
(your) religion compensation monastery home blood bear worms
/dˤ/ maˈdˤiːq ˈdˤɪdˤdˤ ˈdˤeːf ˈdˤaːq ˈdˤɐbtˤ ˈdˤʊħa maʕˈdˤuːdˤ
strait against guest shrunk exactly before noon bitten
/iː/ /aː/ /ə/ /ʊ/ /uː/
MA
/d/ ˈdiːb ˈdaːb dəmˈliːʒ ˈdʊll ˈduːda
wolf melted bracelet humiliation worm
/dˤ/ ˈdˤiːf ˈdˤaːq ˈdˤəbtˤ ˈdˤʊlma ˈdˤuːsˤ
guest shrunk exactly darkness the second
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wide-band spectrogram. In the cases where a sonorant followed the vowel, intensity drop
and visual inspections were used to determine the boundary position of the vowels.
2.2.1 Acoustic analyses
Acoustic analyses were performed automatically using a Praat script designed by the
author and adapted from Al-Tamimi, J. and Khattab (2015). Before performing the
analyses, measurement frame positions of the onset and midpoint of a vowel were
estimated following Al-Tamimi, J. (2004, 2007b) and Al-Tamimi, J. and Khattab (2015)
in order to obtain accurate measurements and reduce errors from the automatic analyses
by computing f
PointProcess (cross-correlation) analysis. Following this, the average length of a complete
times as obtained from the TextGrids (following the segmentation as described above),
length of an average complete glottal cycle. Following this, they were left-aligned to the
original onset estimate, and centered at the original midpoint estimate. The intensity
values, computed every 5 ms, were interpolated before computing the maximum; the
positions. All the reported measurements are obtained at the estimated positions.
Formant frequencies
onset and midpoint of each vowel. These were obtained from a 25-ms Kaiser2 (Gaussian-
requested in the formant analysis using the default Burg algorithm for formant estimation
with a maximum frequency of 5 kHz for male speakers. Following formant estimation,
Praat’s Formant track function was used to reduce the errors in automatic formant
obtained from automatic extraction. When formant tracks obtained through the initial
an LPC smoothed curve obtained from a 256-point zero-padded DFT spectrum computed
from a 10-ms Kaiser2 window left-aligned at the onset or centered at the midpoint of
0.98. Both the FFT and the smoothed LPC displays were used to estimate the position of
a particularly weakened formant.
Bark-dierence formant frequencies
estimated, these were converted to the psychoacoustic Bark scale following Traunmüller’s
(1990) formula 1, where Zn is the Z value (i.e., critical bandwidth) of the formantn, and fn
is the frequency in Hz of the formantn (including f0 in both cases), and any Z values lower
Zc
()
{}
26.81/ 1 1960 / 0.53
nn
Zf
=+−
(1)
()
2.0 : 0.15 2
c
Z Bark Z Z Z
< =+−
(2)
The fundamental frequency f
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quality; there was however a pattern of lower f0 in JA and higher in MA. The estimation
followed the procedure in Al-Tamimi, J. and Khattab (2015) and used the two-pass
pass and the actual f
and 150–200 Hz respectively. The frequencies obtained in Hz were converted to the Bark
scale using formulas 1 and 2. Once the Bark transformation applied on F1, F2, F3, and f0
Z1-Z0, Z2-Z1, and Z3-Z2 at the onset and at the midpoint of the vowel.
Voice quality
was left-aligned at the onset and a second centered at the midpoint of the vowel; these
were then windowed using a Kaiser2 window function. From each windowed interval, a
256-point zero-padded DFT spectrum was computed and the logarithmic power spectral
density, with a bin size of 19 Hz, was computed. Following Al-Tamimi, J. and Khattab
formants were automatically obtained by detecting the highest peaks for a particular
harmonic; maximum amplitude was obtained from f0*0.9 to f0*1.1 and from 2*f0*0.95
to 2*f0*1.05 for H1 and H2, respectively. For the amplitude of the harmonics closest
proposed by Hawks and Miller (1995) instead of using the automatically estimated ones
in Praat due to many errors that prevented manual correction. Then maximum amplitudes
were obtained in the region from F1 – 0.5*Bandwidth1 to F1 + 0.5*Bandwidth1 for
A1. The same procedure was applied for A2 and A3 (and using Bandwidths 2 and 3
respectively). The automatic detection of formant frequencies, and highest peaks were
harmonics, we relied on the normalization procedure as developed by Iseli et al. (2007)
and implemented in our Praat script to obtain the ‘corrected’ versions of these harmonics
H1, H2, A1, and A2 were
A3 was normalized by
H1*-H2*, H1*-A1*, H1*-A2*, H1*-A3*, A1*-A2*, A1*-A3*, and A2*-A3* at both onset
and midpoint of the vowel.
2.2.2 Statistical analyses
A total of 30,966 measurements (17,992 in JA and 12,974 in MA) were obtained from
onset and midpoint (i.e., a total of 26 measures). Our main aim in this study is to evaluate
the degree to which a particular acoustic correlate can be used to successfully predict the
adopted a predictive approach (Baguley, 2012; Hastie et al., 2009; Kuhn & Johnson, 2013).
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which acoustic correlate(s) are the most predictive of the two consonant categories. All
analyses were run using the statistical software (version 3.3.1) (R Core Team, 2016).
Generalized Linear Mixed-Effects Modeling (GLMM)
Before running the GLMMs, we started by examining the correlation levels in our data. We
used correlation matrices ordered by hierarchical clustering obtained with the function
hclust from the package reshape2R
script (Melike, 2016). These correlation matrices are presented in Appendix 1 for JA and
in Appendix 2 for MA. The correlation matrices showed that out of the total combinations
p < 0.01, i.e., any absolute
r2p values obtained with the function rcorr
from the package Hmisc (Harrell Jr, 2016)). In both dialects, voice quality and formant-
based measures are negatively correlated with each other, and all formant measures
JA, where Z3-Z2 is negatively correlated with Z2 and Z2-Z1). Given the recommendations
in Baayen (2008, p. 181–183), it was not advisable to use all these measures together
in a regression analysis as they will be giving either the same outcome (in the case of
positively correlated ones) or cancel each other out (for negatively correlated cases).
Hence we decided to use separate regression analyses on each of the individual acoustic
correlates and compared these via predicted probabilities. In addition, due to the high
predictive outcome of some acoustic correlates (e.g., F2, Z3-Z2, see below), it was not
possible to use one GLMM model combining all the acoustic correlates, as these were
canceling each other out, resulting in model non-convergence.
Due to these constraints (multicollinearity and high predictive power), we used an
measures are already on logarithmic scales). We obtained the descriptive statistics using
the package psycholing (Fraundorf, 2015), with the means and standard deviations
for the original and z-scored values. The z-scored values were computed to a mean of 0
and a standard deviation of 1, separately for each dialect (using the means and standard
deviations presented in column “All” in Table A3 in Appendix 3 that provides a summary
mean and standard deviations in the original and the z-scored scale. We also included the
of the outcome with the results of the GLMMs).
Following this, and to avoid multicollinearity, we ran separate GLMMs on the individual
z-scored acoustic correlates following Schielzeth (2010) as a simple and meaningful
running GLMMs with the ‘consonant’ as a binomial response category (dummy coded
with /d/ = = 1), and the separate acoustic correlates as predictors (i.e., a
the GLMM and allows for a meaningful interpretation of the results with the
β
of the
Intercept representing the average in the /d/ environment whereas the predictor’s
β
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For the random part of the model, we used speakers and items as crossed random factors
(Baayen et al., 2008). Within item variation with respect to repetitions was included to
allow for this random variation to be taken into account. Both by-speaker and by-item
These allowed both speakers and words to vary with respect to the within variation that is
due to the acoustic correlates. By-item random slopes were necessary given that we only
had one item per consonant and vowel combination; this allowed the acoustic correlates
to vary within each word, otherwise the model would inaccurately overestimate this
variation. In many occasions, random intercepts for words were not successful at providing
a clear picture of the results, and hence were dropped, i.e., only a by-item random slope
was used.
To prevent quasi- and complete separation of the data that was obtained with lme4
as implemented in the package blme (Chung et al., 2013). The function bglmer requires
xef.prior = normal(cov = diag(2.5,2)), with 2
parameters and 2.5 representing a variance of 2.5 which is equivalent to a 1.58 SD that is
close to our actual SD for the z-scored data (being 1SD) (following the recommendations
kept at its default, (i.e., cov.prior = wishart, for more detail, see Chung et al., 2013).
Random Forests via Conditional Inference Trees
predictive model (Hastie et al., 2009; Kuhn & Johnson, 2013). Random Forests are one
of the most versatile machine learning algorithms as they do not require many tunings of
their settings. They have been applied to sociolinguistic data (for a detailed description
of these methods, see Tagliamonte & Baayen, 2012), and also to acoustic cue weighting
in perception (Brown et al., 2014). Random Forests were originally proposed by Breiman
(2001) as an ensemble learning algorithm that uses independent
trees in growing a forest. The independence stems from the randomness of the selection
a decision tree is constructed. This is then repeated several times (for the total number
2002). After the forest is grown, one can estimate the prediction accuracy as well as the
ranking of the most important predictors. This model can also be used to predict the
outcome on new unseen data, e.g., newly collected production/perception data or on the
testing set (out-of-bag set). The algorithm splits the data into learning and testing sets; the
in-bag set, while the latter
out-of-bag set. Then subsampling
without replacement is used in growing the forest (for more details, see Strobl et al., 2009).
Instead of using the original implementation of Random Forests available in the
R package randomForest (Liaw & Wiener, 2002), we used Random Forests grown
from Conditional Inference Trees as implemented in the package party (Hothorn et
al., 2006; Strobl et al., 2008, 2007). Strobl et al. (2008, 2007) found that the original
randomForest provided biased estimates of Random Forests’ variable importance (see
below) as it was biased towards variables with multiple categories and multiple cut-points,
and also overestimated variable importance measures when correlated data is used (as is
the case in our study). To guard against this bias, they developed an unbiased selection
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process (subsampling without replacement). This form of random forests, i.e., based on
conditional inference trees, are well suited to deal with collinear variables (Strobl et al.,
2008, 2007; Tagliamonte & Baayen, 2012), with “‘small n large p’ case, where the number
of predictor variables p n” (Strobl et al., 2009,
by ranking them after controlling for interactions and collinearity.
Random Forests were run using the party package with the function cforest on the
recommended cforest_unbiased control with mtry = 5 (rounded square root of 26
ntree can be tuned to allow for less computation time, and
we followed the density-based metrics developed by (Oshiro et al., 2012) to estimate the
density of our dataset using the formula 3, with an
of observations and c
{}
log /
a
Density n c
= (3)
For JA and MA, the density-based metrics were equal to 1.79 and 1.69 respectively.
According to Oshiro et al. (2012), these values constitute a low density database. The
authors found that a large number of trees close to and above 2000 is only needed with
high density datasets that exceed a density-based value of 3. A low number of trees
(ntree
predictive accuracy. Hence, we implemented the same procedure as that suggested by
by using ntree from 100 to 1500 in a 100 trees increment. Then for all generated random
forests, we checked their predictive power, by using the function predict using the
out-of-bag set as a cross-validation (using OOB = TRUE). Then we used an AUC (for Area
Under the Curve) based comparison using the package pROC (Robin et al., 2011), by
generating an ROC curve (for Receiver Operating Characteristics) and then by performing
roc.test, following DeLong et al. (1988). The results of this comparison showed that for
JA, 400 trees were enough to reach the highest predictive accuracy, whereas for MA, 300
trees were enough. Hence we ran random forests with these ntree values.
Then we used an AUC-based estimation of the variable importance, varimpAUC
as it takes into account both accuracy and error of estimation and used conditional
permutation tests with conditional = T
et al., 2008, 2009). We then evaluated how well correlated are the random forest results
out-of-bag
cross-validation.
After this initial random forest using all of the acoustic correlates, we ran six additional
exploratory random forest analyses that will be used for their predictive accuracy. These
the type of acoustic correlates used. We compared formant-based metrics only, i.e.,
The aim here is to evaluate the strength of these metrics at separating the two categories.
in addition to voice quality, in order to assess whether there is an increase/decrease in
of the voice quality metrics on their own, in order to evaluate whether any observed
categories. In each case, we used the above procedure to estimate the optimal number of
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trees needed to obtain the highest predictive accuracy, and adapted mtry to each case.
The next section presents the results of this study.
3 Results
3.1 GLMM
acoustic correlate as a predictor (i.e., a Full model) and a second without the acoustic
ratio tests to derive all p values (Barr et al., 2013) and to test whether a particular acoustic
Table 3
(as a reference, complete descriptive statistics of the results are presented in the Table A3
in Appendix 3). Figures 1, 2, 5, and 6 were generated using the predicted probabilities
of the individual acoustic correlates as obtained from the Full GLMM. These predicted
probabilities were obtained from the predict function in blme based on a new dataset
with the range between –3 and 3 z
an R
lattice (Sarkar, 2008), latticeExtra (Sarkar & Andrews, 2016) and gridExtra
(Auguie, 2016). Using this range allows for a meaningful comparison between all the
measures. When looking at the predicted probability curves, we will refer to a sigmoidal
linear shape. A sigmoidal curve indicates a high level of separation between the groups
each acoustic correlate, the absolute
β
size; the negative or positive signs are indicative of falling or raising probability curves
Figure 1 shows the predicted probabilities for Z1, Z2,
and Z3 at both onset and midpoint of the vowel in JA (blue solid) and MA (red dashed). In
both dialects, Z1 at the onset of the vowel shows raising curves from /d/ (values starting
from –3 zz-score); Z2 shows the reverse pattern,
z-score) to /d/ (values ending with
+3 z
–3 zz-score), although the shape is not as sigmoidal
GLMM based on the
β
β
β
3.1.1 Absolute Formants
From model comparison results (see Table 3), it can be seen that F1 and F2 at the onset and
and non-pharyngealized consonants. In MA, F3 at the midpoint only showed a tendency
in the literature; F1 shows an increased
β
as displayed in Figure 1 show a clear pattern of rise, fall, rise patterns for F1, F2, and F3;
z
size measures (Schielzeth, 2010). In JA, F2 at the onset has the highest absolute
β
value and
shows more of a sigmoidal curve (see Z2 Onset, Figure 1). In MA, however, F1 mid and F2 at
both onset and mid have the highest absolute
β
values and show a near complete sigmoidal
curve. When converting the
β
values to percent correct, all four acoustic correlates (in JA
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Table 3: Summary of statistical results, with model comparison between Null and Full models, with χ2 (1 df), and p values, followed by the GLMM results
of the Full model with the estimates of the Fixed effect of each acoustic measure (with
β
, SE (Standard Error), Wald’s z value, associated p value, and %
correct classification based on
β
values); significant results are in bold.
JA MA
Model comparison GLMM results Model comparison GLMM results
χ2 (1) p β SE z Pr (>|z|) % χ2 (1) p β SE z Pr (>|z|) %
Z1 Onset 8.07 <0.005 1.28 0.47 2.71 <0.007 78.26 24.2 <0.00001 2.05 0.32 6.51 <0.00001 88.63
Mid 8.18 <0.005 2.39 0.97 2.46 <0.02 91.62 25.51 <0.00001 4.54 1.04 4.38 <0.00001 98.95
Z2 Onset 27.38 <0.00001 –6.92 0.92 –7.51 <0.00001 99.90 30.88 <0.00001 –4.59 0.64 –7.23 <0.00001 99.00
Mid 10.303 <0.001 –1.55 0.77 –2.00 <0.05 82.43 2.9403 =0.086 –4.79 0.67 –7.17 <0.00001 99.17
Z3 Onset 0.27 =0.61 0.12 0.29 0.40 =0.70 52.91 0.75 =0.39 0.16 0.22 0.74 =0.47 53.96
Mid 0.46 =0.50 0.17 0.24 0.69 =0.49 54.19 3.26 =0.071 0.56 0.32 1.74 =0.082 63.66
Z1-Z0 Onset 12.38 <0.0001 1.36 0.38 3.59 <0.0001 79.55 20.58 <0.00001 1.85 0.31 6.03 <0.00001 86.38
Mid 6.65 <0.01 2.07 0.94 2.20 <0.05 88.78 27.61 <0.00001 4.50 0.97 4.63 <0.00001 98.90
Z2-Z1 Onset 26.15 <0.00001 –6.09 0.90 –6.74 <0.00001 99.77 30.1 <0.00001 –4.65 0.56 –8.23 <0.00001 99.05
Mid 39.622 <0.00001 –3.77 1.70 –2.22 <0.05 97.75 13.327 <0.0005 –2.58 0.85 –3.04 <0.002 92.95
Z3-Z2 Onset 22.94 <0.00001 6.35 1.03 6.15 <0.00001 99.83 28.37 <0.00001 4.38 0.58 7.58 <0.00001 98.76
Mid 8.5688 <0.005 1.55 0.56 2.76 <0.006 82.46 22.109 <0.00001 4.75 1.07 4.45 <0.00001 99.15
H1*-H2* Onset 0.29 =0.60 0.09 0.19 0.49 =0.62 52.32 0.06 =0.81 0.05 0.18 0.26 =0.42 51.15
Mid 0.03 =0.87 0.05 0.19 0.28 =0.78 51.34 0.88 =0.35 0.14 0.17 0.81 =0.80 53.52
H1*-A1* Onset 2.56 =0.11 –0.41 0.27 –1.49 =0.14 60.02 22.46 <0.00001 –1.51 0.23 –6.41 <0.00001 81.83
Mid 8.27 <0.005 –0.58 0.21 –2.74 <0.006 64.07 13.68 <0.0001 –1.33 0.34 –3.93 <0.0001 7 9 .1 0
H1*-A2* Onset 10.35 <0.001 –0.76 0.23 –3.34 <0.001 68.24 19.74 <0.00001 –1.98 0.33 –6.05 <0.00001 87.82
Mid 5.76 <0.02 –0.61 0.26 –2.29 <0.05 64.73 17.63 <0.00001 –1.46 0.32 –4.60 <0.00001 81.14
H1*-A3* Onset 3.18 =0.074 0.25 0.15 1.65 =0.098 56.31 4.03 <0.05 –0.32 0.18 –1.82 =0.068 58.00
Mid 2.07 =0.15 0.05 0.19 0.28 =0.17 51.34 1.93 =0.17 –0.27 0.22 –1.25 =0.21 56.69
A1*-A2* Onset 2.54 =0.11 –0.42 0.28 –1.51 =0.13 60.32 5.74 <0.02 –0.69 0.28 –2.44 <0.02 66.56
Mid 0.79 =0.37 –0.16 0.19 –0.80 =0.42 53.88 13.18 <0.0001 –0.80 0.21 –3.77 <0.0002 68.97
A1*-A3* Onset 11.04 <0.001 0.77 0.22 3.55 <0.0005 68.36 2.23 =0.14 0.33 0.24 1.39 =0.17 58.24
Mid 0.17 =0.68 0.09 0.21 0.43 =0.67 52.29 1.16 =0.28 0.30 0.29 1.04 =0.30 57.37
A2*-A3* Onset 16.66 <0.00001 1.23 0.24 5.07 <0.00001 77.40 11.39 <0.001 1.01 0.27 3.74 <0.0002 73.37
Mid 1.72 =0.19 0.41 0.34 1.20 =0.23 60.17 4.01 <0.05 0.96 0.52 1.85 =0.065 72.28
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obtained for the absolute formant frequencies are comparable in direction and range to the
previous literature (see Table A3 in Appendix 3 and Section 1.1.1).
Following perturbation theory and the acoustic theory of speech production (Carré
Johnson, 2012; Mrayati et al., 1988; Stevens, 1989), the location of the constriction
responsible for producing pharyngealization is predicted to be located in the pharyngeal
area, potentially between the upper to mid pharynx, as is generally reported in the
vowels (by around 70 Hz) and a raised F3 in back vowels (by around 200 Hz) from
2009) (see also Section 2.2.1).
3.1.2 Bark-difference formants
divergence of vowels (Fahey et al., 1996; Hoemeke & Diehl, 1994; Sylak, 2011; Syrdal
& Gopal, 1986; Traunmüller, 1981; Wood, 1986). Model comparison results summarized
in Table 3
show increased
β
values, whereas Z2-Z1 shows lowered ones. The predicted probabilities
presented in Figure 2
with variable degrees of separation. Generally, MA shows higher
β
values for Z1-Z0 and
(see absolute formant frequencies results in Figure 1 above).
being associated with a lowered Z2-Z1. A low pharyngeal constriction will show Z2-Z1
values below 3 Bark values whereas a mid to upper pharynegal constriction will show
higher Z2-Z1 values around 4.6 Bark (Al-Tamimi, F. & Heselwood, 2011; Heselwood &
Al-Tamimi, F., 2011). Our results show a lowering of Z2-Z1 values that is close to the
Figure 1: Predicted probability curves spanning –3 to +3 z-score for absolute formant frequencies
in both JA (blue solid) and MA (red dashed). Falling curves indicate a lowering in the predicted
probabilities from /d/ to /d/ (as in Z2) and vice versa. The reference line (in gray) indicates the
non difference line.
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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Art. 28, page 20 of 40
β
values at the Onset
for JA and at both positions in MA. They show a more retracted vowel quality that is
correlate to the already lowered Z2-Z1. The predictive strength of these correlates is
Table 3 for more detail).
3.1.3 Vowel spaces
We used relational formant frequencies to display vowel spaces; using the traditional
F2*F1 (in Bark) vowel spaces and that of Z3-Z2*Z2-Z1 at both onset and midpoint of the
Figures 3 and 4 show both Z2*Z1 (a) and Z3-Z2*Z2-Z1 (b) at onset (top) and midpoint
(bottom) in both JA and MA respectively (charts generated with the package phonR,
Glassman, 2014b).
Vowel spaces at the onset provide the clearest separation between the two categories
compared with that at the midpoint, although in MA, the midpoint results lend support
Figure 4). At the onset, JA shows a clear back vowel
quality as represented with absolute F2, whereas MA shows a clear open and back vowel
articulation through absolute F1 and F2 respectively (see Figures 3a and 4a). Moving on
Figures 3b and 4b), and particularly at the onset (top),
both JA and MA show a clear separation between the two categories, with vowels in the
pharyngealized context showing a ‘compact’ (with lower Z2-Z1) and ‘backed’ (with higher
Z3-Z2) production; they are ‘retracted’ in the sense of the Laryngeal Articulator Model
(Esling, 2005; Moisik et al., 2012; Sylak-Glassman, 2014b). By using absolute formants
only (Figures 3a and 4a
all vowels seem to range around 4 Bark. Our claim is then if one is to acoustically evaluate
Figure 2: Predicted probability curves spanning –3 to +3 z-score for Bark-difference formant
frequencies in both JA (blue solid) and MA (red dashed). Falling curves indicate a lowering in
the predicted probabilities from /d/ to /d/ (as in Z2-Z1) and vice versa. The reference line (in
gray) indicates the non difference line.
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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the predictions of the Laryngeal Articulator Model, absolute formant frequencies alone
are not useful at showing the ‘retraction’ that has a combined back and down gesture;
Figure 4: Absolute formant (Z1*Z2; a) Versus Bark-difference (Z2-Z1*Z3-Z2; b) Vowel spaces at
onset (top) and midpoint (bottom) of /d/ (red solid) and /d/ (blue dashed) in MA.
Figure 3: Absolute formant (Z1*Z2; a) Versus Bark-difference (Z2-Z1*Z3-Z2; b) Vowel spaces at
onset (top) and midpoint (bottom) of /d/ (red solid) and /d/ (blue dashed) in JA.
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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3.1.4 Voice quality
associated with pharyngealization in Arabic (although see Alwan, 1986, 1989, on the
estimated bandwidth in pharyngeals). Our voice quality results are separated into spectral
slope and high frequency energy (Figures 5 and 6 respectively). Starting with spectral
slope, model comparison results suggest that H1*-A1*, H1*-A2*, and H1*-A3*, in either
consonants in both dialects (Table 3). GLMM results show an overall decrease in
β
values
H1*-A3* Onset
in JA). MA results show a stronger contribution of these metrics to the distinction between
the consonants compared to JA. This is shown further in the curve shape in Figure 5 where
H1*-A1*, H1*-A2* at both onset and midpoint show a near sigmoidal curve, although this
β
and a predictive
Table 3). These spectral slope measures seem to act as
secondary correlates to pharyngealization as they do not show the same predictive power
as formant frequencies.
voice quality that is related to a greater glottal constriction (Keating et al., 2015). This leads
to variation in the bandwidths of F1 and F2 (through H1*-A1* and H1*-A2* respectively)
that accompanies tense/pressed voice quality; an increased bandwidth of F1 and F2
causes a decrease in the amplitude of the harmonic closest to F1 and F2, respectively
H1*-A3* is indicative
Keating, 2012). This seems to be the case with MA as a more abruptly constricted glottis
H1*-A3* (Hanson & Chuang, 1999; Hanson et al., 2001). For JA however, the increased
Figure 5: Predicted probability curves spanning –3 to +3 z-score for Spectral slope results in
both JA (blue solid) and MA (red dashed). Falling curves indicate a lowering in the predicted
probabilities from /d/ to /d/ (as in H1*-A1*) and vice versa. The reference line (in gray) indicates
the non difference line.
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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H1*-A3* is indicative of a lowered energy around F3 in the pharyngealized context, which
seems to correlate well with the predictions of a constricted glottis with a simultaneous
front to back closure along the length of the vocal folds (for more detail, see e.g., Hanson
& Chuang, 1999; Hanson et al., 2001; Klatt & Klatt, 1990; Stevens, 1998). Both dialects
display tense voice quality that is associated with pharyngealization though spectral slope
is; abrupt in MA and with a simultaneous front to back closure of the vocal folds in JA.
Moving on to high frequency components, and through model comparison (Table 3),
two consonants. In JA, only A1*-A3* and A2*-A
in MA, it is A1*-A2* and A2*-A3* at the onset and midpoint. This can also be seen from
the predicted probabilities as shown in Figure 6 where some curves are near sigmoidal,
β
and percent correct values)
are small compared to formant based measures, and these high frequency components
A1*-A2* is correlated
with a constriction closer to the tongue root (i.e., mid to lower pharynx) as is the case
in languages with [–
1998; Guion et al., 2004; Kang & Ko, 2012, among others). This suggests that in MA, a
lower constriction location for pharyngealization may be in operation, although a non-
A1*-A2* at the onset in JA is obtained. With respect to the two
other metrics, an increase in A1*-A3* and A2*-A3* is observed in both JA and MA with
raised predicted probabilities (see Figure 6). This increase is indicative of a relatively
decreased energy around F3 with respect to that of F1 or F2. In fact, A1 and A2 are
already high in energy due to the pharyngeal constriction, and the change observed in
A3 energy would be indicative of a change due to the epilaryngeal constriction that leads
and the high frequency components are indicative of a constricted epilarynx; the former
shows acoustic correlates of a tense voice quality, and the latter a constricted epilarynx
with a relative increase in A1*-A3* and A2*-A3* due to decreased energy around F3.
This combination suggests that pharyngealization in Arabic is associated with constricted
ventricular folds (Moisik et al., 2012; Moisik & Esling, 2011; Sylak-Glassman, 2014a). This
constriction of the glottis leads to a tense voice quality that is potentially associated with
Figure 6: Predicted probability curves spanning –3 to +3 z-score for the High frequency
components in both JA (blue solid) and MA (red dashed). Falling curves indicate a lowering in
the predicted probabilities from /d/ to /d/ (as in A1*-A2*) and vice versa. The reference line
(in gray) indicates the non difference line.
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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Art. 28, page 24 of 40
a constricted and/or raised larynx posture (Klatt & Klatt, 1990; Laver, 1994; Sundberg &
Askenfelt, 1981). These novel acoustic consequences require further investigation from an
articulatory point of view to shed light into this secondary correlate of pharyngealization
in Arabic.
3.1.5 Summary of results
The results presented above showed the vowels in the vicinity of pharyngealized consonants
in Arabic to be ‘retracted’ (Esling, 2005; Sylak-Glassman, 2014a, b). They are produced as
more open (higher F1, Z1-Z0) and more back (lower F2, higher Z3-Z2), with a constriction
in the pharyngeal area that causes compaction of the spectrum (lower Z2-Z1), and spectral
divergence as an enhancing correlate to the compacted spectrum (higher Z3-Z2). Z2-Z1
seems to provide a better combined correlate to the compaction of the spectrum rather
than the separate F1 and F2, although both are related to each other (see Section 3.1.3).
Our novel results with respect to spectral slope and the high frequency components seem
to suggest that pharyngealization in Arabic is associated with a secondary constricted
ventricular folds and hence a constricted epilarynx; this induces a tense voice quality with
lower H1*-A1*, H1*-A2*, H1*-A3*, and A1*-A2*, and an increased A1*-A3* and A2*-A3*
due to the decreased energy around F3. This is caused by a secondary constriction of the
Given that we used individual GLMM analyses due to the constraints of our data (high
collinearity), the individual
β
and percent correct values provided some insights into the
discriminatory power of each of these acoustic correlates. However, it is not clear how
these behave together and which acoustic correlates are more informative than the others.
that will shed light into the discriminatory power of the combined acoustic correlates.
3.2 Random Forests
The results presented in the previous section showed that none of the acoustic correlates
β
=
all 26 acoustic correlates (the 13 acoustic correlates at both onset and midpoint) in the
actual data). Overall, the random forest analysis correlated well with our actual data
22
After running the random forest analysis, we used the predict function from the party
package to provide predictions based on the out-of-bag
specifying OOB=TRUE. This allows the algorithm to train itself on two-thirds of the data
(the in-bag set), and then to use the remaining third of the data (the out-of-bag set) for
out-of-bag
Following this, we ran conditional permutations variable importance to measure
the strength of each of the acoustic correlates conditional on each other and by using
varimpAUC and conditional=TRUE. Figure 7
a particular acoustic correlate is removed.
The results show a clear separation between formant-based and voice quality-based
measures with the former being highly predictive of the two consonant category
(Figure 7). Looking at the results in detail, the ranking of the predictors in JA (Figure 7a)
shows that F2 Onset, Z3-Z2 Onset, followed by Z2-Z1 Onset, are the most important
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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correlates, whereas in MA (Figure 7b), Z2-Z1 Onset followed by F2 Onset, and Z3-Z2
Onset are the most important. All the other correlates have lower values and thus can be
when compared with the GLMM results above, MA potentially shows more mid-lower
pharyngeal constriction, while JA shows mid-upper pharyngeal constriction. More
JA showing a score of 0.027 of the conditional mean decrease in accuracy when F2 Onset
is removed, whereas in MA it is a 0.015 decrease for F2 Onset. These results correlate well
with the
β
values presented in the GLMM results (see Section 3.1).
are only used for their predictive accuracy. Table 4 provides a summary of the predictive
accuracy of each of these additional random forests and as a comparison, the results of the
between the two contexts. This is to be expected as pharyngealization is primarily
formant-based metrics have the most explanatory power, and may be suggestive of a
Figure 7: Mean decrease in accuracy importance scores in JA (a) and MA (b).
Table 4: Summary of predictive accuracy as classification rate for each of the random forests in
JA and MA.
Form + BkDiff + VQ Form + BkDiff Form BkDiff Form + VQ BkDiff + VQ VQ
JA 93.5% 93.2% 92.1% 92.9% 92.2% 93.1% 70.2%
MA 91.1% 91.0% 90.5% 90.8% 90.6% 91.0% 75.8%
Form = Absolute Formants; BkDiff = Bark-Difference formants; VQ = Voice Quality.
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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Art. 28, page 26 of 40
metrics to absolute ones (either on their own or combined with voice quality), the results
metrics as showing the same patterns; they are both indicative of [+
[+
pharyngealization, as the GLMM results summarized above (see Figures 3b and 4b)
quality of the vowels in the pharyngealized context, following LAM (Esling, 2005;
Sylak-Glassman, 2014a, b). Overall, the ranking of the various metrics was comparable
to those reported in the full model (see Figure 7). However when absolute formants
were used on their own, F2 at the Onset was the main correlate in both dialects. As
expected, these results point to the fact that formant-based metrics are the primary
correlates to pharyngealization in JA and MA.
Finally, the predictive accuracy of voice quality metrics on their own was assessed. The
results presented in the last column of Table 4 suggest that in both JA and MA, voice
metrics, but provide support for voice quality metrics to act as a secondary correlates
to pharyngealization. The ranking of correlates (not presented here) matches what we
already saw in Figure 7, in that A1*-A3*, A2*-A3*, H1*-A1*, H1*-A2* are the most
predictive acoustic correlates in both dialects. However, in MA, spectral slope correlates
are used more than in JA, and JA tends to use more the high-frequency components more.
In both dialects, voice quality measures are indicative of an epilaryngeal constriction used
as a secondary articulatory setting with formant-based metrics being the best predictors.
4 Discussion and Conclusion
This exploratory study is aimed at investigating whether pharyngealization in Arabic is
associated with an epilaryngeal constriction from an acoustic perspective. Traditionally,
pharyngealization in Arabic is generally assumed to involve tongue body (dorsum)
retraction towards the upper-pharyngeal areas that leads to a lowering of the second
formant in the surrounding vowels (e.g., Bin-Muqbil, 2006; Ghazeli, 1977; Watson, 2007;
Zawaydeh, 1999; Zawaydeh & de Jong, 2011). However, both classic and more recent
articulatory evidence show this constriction to be located much lower in the pharynx,
with epiglottis retraction, and raising of the larynx that leads to a pressed/tense voice
quality (see e.g., Al-Tamimi, F. & Heselwood, 2011; Cantineau, 1960; Hess, 1998; Laufer
& Baer, 1988; Lehn, 1963; Zeroual & Clements, 2015; Zeroual et al., 2011, among others).
Following the Laryngeal Articulator Model (Esling, 2005), ‘true’ pharyngeals seem
the aryepiglottic folds. Pharyngealization on the other hand seems to show this type of
constriction albeit as a secondary one with a primary pharyngeal constriction (Esling,
are usually investigated (see Section 1.1.1 above). However, these are only indicative of
a pharyngeal constriction and do not directly explain any voice quality correlates that are
a by-product of an epilaryngeal constriction. An epilaryngeal constriction is expected to
back and down movement of the tongue as well as laryngeal
muscles constriction (Esling, 2005; Moisik, 2013a; Sylak-Glassman, 2014a, b).
This study investigates the absolute formant frequencies, which is typical of such
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pharyngealization in Arabic. Our results with respect to absolute formants are in agreement
with previous literature, with vowels in the pharyngealized context showing decrease in
F2 and an increase in F1 regardless of the vowel quality. In addition, F3 shows an overall
increase in both dialects, but seems to show lowering when the vowel is front, and rising
when the vowel is back (see Section 3.1.1 and Figure 1). Using the Distinctive Regions
Model (DRM) (Carré & Mrayati, 1992; Mrayati et al., 1988) that is based on the principles
location based on the acoustic output. When F1 is rising, F2 is falling, and F3 is rising as
in back and central vowels, the location of the constriction is close to the DRM region R4
in the upper pharynx. A combination of rising F1, and falling F2 and F3 seems to be close
to the DRM region R3 in the mid-lower pharynx (see e.g., Carré & Mrayati, 1992, Figure 8,
p. 150 and Figure 12, p. 156). These acoustic results are compatible with the articulatory
accounts presented in Ghazeli (1977, p. 174, as cited in Laufer & Baer, 1988, p. 55)
that ‘emphatic’ consonants have a secondary tongue retraction located midway between
uvulars and pharyngeals.
Following the predictions of the Laryngeal Articulator Model (Esling, 2005; Sylak-
Glassman, 2014a, b) pharyngealization is associated with a retracted production that has
a combined back and down
is expected to observe both a lowering of F2 and a rising of F1 as a combined acoustic
consequence. Thus the distance between these two formants can be seen as an alternative
metrics, e.g., Z1-Z0 and Z3-Z2 as correlates of a more open and a more back articulation
and these correlated well with the traditional F1 and F2 dimensions separately. These
by the acoustic vowels spaces (see Figures 3 and 4).
mid pharyngeal constriction. Compared to /d/, Z2-Z1 in the pharyngealized context was
Appendix 3), which is close to the range reported in other studies (see e.g., Al-Tamimi,
indicative of a much higher constriction location than ‘true’ pharyngeals that have a
smaller distance of about 3 Bark. Z1-Z0 and F1 results in both dialects are indicative of a
118 Hz) that correlates well with a one-degree change on the openness dimension agrees
with the similarity scales between vowels and pharyngeals or uvulars as reported in Sylak-
Glassman (2014b). When in contact with either category, vowels tend to be produced with
with spectral integration (Fahey et al., 1996; Traunmüller, 1983, 1984). When dealing
with ‘phonetically’ similar vowels, i.e., allophones changing in quality due to (non-)
pharyngealization, a Z2-Z1 distance close to or below 6 Bark signals spectral integration
(Traunmüller, 1983, p. 5–6). This as a whole leads to the conclusions that Z2-Z1 seems to
be the
below the 3.5 Bark threshold for spectral integration (Chistovich & Lublinskaya, 1979;
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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Art. 28, page 28 of 40
show a clear separation between the F2 and F3 due to the extremely lowered F2 and the
the pharyngealized context is acting as an enhancement feature to the already spectrally
integrated peak, i.e., Z2-Z1.
The combination of these three psychoacoustic metrics at the onset of the vowels in
the pharyngealized context seems to show a direct psychoacoustic manifestation of
the [+
1952/1976) as an acoustic correlate to pharyngealization. Z2-Z1 seems to be the main
psychoacoustic correlate as it is close and below the threshold for spectral integration,
Z3-Z2 seems to play a role as an enhancement feature and Z1-Z0 seems to correlate well
with the more open articulation.
A second articulatory consequence of an epilaryngeal constriction is voice quality
changes. Ventricular folds constriction leads to a tense, harsh, laryngealized voice quality,
whereas an aryepiglottic constriction leads to ‘trilling’ as seen in ‘true’ pharyngeals
and an ‘enhanced’ voice quality (Edmondson & Esling, 2006; Esling, 1996; Moisik,
2013a, b; Moisik et al., 2010; Story, 2016). Our results with respect to voice quality
correlates—spectral slope and tilt—provide a secondary description to pharyngealization
in Arabic. Pharyngealization is associated with a tense voice quality that is caused by
constricting the intrinsic muscles of the larynx—the ventricular folds (see e.g., Garellek,
2012; Hanson & Chuang, 1999; Hanson et al., 2001; Keating et al., 2015; Kuang & Keating,
2012). Our estimated F1 and F2 bandwidths correlate well with a tense/pressed voice
quality through a decrease in H1*-A1* and H1*-A2* metrics (Garellek, 2012; Hanson
bandwidth was found in pharyngeals but an increased F1 bandwidth in uvulars. Our
and
uvulars through the combined increase in the bandwidths of F1 and F2. Finally, a lowered
H1*-A3* is also suggestive of a tense voice quality through an abrupt constriction of the
Klatt & Klatt, 1990). In JA, an increase in H1*-A3* is indicative of an increased spectral
tilt and partially reduced energy around F3; consequences of a constricted glottis with a
simultaneous front to back closure of the vocal folds (Hanson & Chuang, 1999; Hanson et
al., 2001). This also seems to correlate well with a tense/pressed voice quality (Garellek,
2012; Hanson et al., 2001; Keating et al., 2015; Kuang & Keating, 2012).
The high frequency components provide an additional correlate to the glottal constriction
through a constricted epilarynx and this constriction provides additional energy to the
upper formants when comparing the two categories (Halle & Stevens, 1969; Stevens, 1977;
Story, 2016). Our results showed that in both JA and MA an increased A1*-A3* and A2*-
A3* is found. This is caused by a decrease in the energy around F3 that is potentially caused
by the type of constriction in the glottis. Constricting the epilarynx on its own would lead
the harmonics closest to F3, F4, and F5. This is seen in the singer’s formant—a primary
technique used in signing to enhance the voice quality (Story, 2016; Titze & Story, 1997).
In our case, constricting the epilarynx is secondary; pharyngeal constriction leads to a
boost in the energy around F1 and F2, and the changes seen with respect to F3 will
be minimal. This causes a decrease in the energy around F3 leading to the increased
A2 and A3 more than what
is seen in A1; the latter is relatively higher in amplitude that the former. Their harmonic
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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here; a relatively increased A1*-A3* and A2*-A
to the normal setting (Liénard & Di Benedetto, 1999, Figure 3, p. 416). In this particular
comparable to what is seen in tense voice. Finally, and according to Story (2016, Figure 7,
p. 10), a constricted epilarynx would lead to an increase in the frequency and amplitude
of F3 to make it move closer to F4. This closeness correlates with the singer’s formant and
changes the ‘timbre’ or quality of voice of a particular speaker. F1 and F2 are responsible
for the phonetic quality of a vowel, whereas voice quality is manifested through F3 to F5
frequencies and amplitudes. Hence if we postulate that pharyngealization is associated with
an epilaryngeal constriction, F3 to F5 amplitude and frequencies should be investigated as
well. This future work is currently planned on a forthcoming dataset.
results showed a clear separation between formant-based and voice quality-based measures.
pharyngealization in Arabic as involving a constricted glottis through constriction of the
the vowel quality into a more open (high F1 and Z1-Z0), a more compact (low Z2-Z1),
a more retracted (low F2, and high Z3-Z2) with spectral integration (low Z2-Z1) and
and spectral divergence, while in MA it is a combined F1 and F2-based through a more
compact spectrum with retraction. When considering absolute formant frequencies alone,
both dialects display the same pattern i.e., F2-based followed by F1-based; results that
is implemented (with some dialects having a more ‘guttural’ quality) can be evaluated
JA (see e.g., Bellem, 2007; Embarki et al., 2011), though it is not clear whether these
More detailed articulatory and acoustic description is required to shed light into these
4.1 Implications for formal representations
[
(Lindau, 1975, 1978); [
[
(Czaykowska-Higgins, 1987); [
2015); [
(Shahin, 1996, 1997, 2011; Watson, 2007). This list is not exhaustive, however, it highlights
the activity of the retraction of the root of the tongue. It is not clear however whether
this retraction causes only lowering of F2 frequencies (i.e., Z2 and Z3-Z2) or whether it
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
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Art. 28, page 30 of 40
accounts for the more open production with rising of F1 (i.e., Z1, Z1-Z0). In addition,
by [+
for by [+
[+
that the tongue retraction as seen here is a by-product of constricting the epilarynx (e.g.,
Esling, 2005; Moisik, 2013a; Sylak-Glassman, 2014a, b, and Section 1.2), we follow Moisik
et al. (2012), Moisik and Esling (2011), and Sylak-Glassman (2014a) and postulate that
pharyngealization in Arabic is produced by an epilaryngeal constriction that causes the
tongue root and body to be retracted by a back and down gesture. This induces a laryngeal
constriction leading to a raised larynx posture and a tense/pressed voice quality. Based on
these descriptions and on our results, pharyngealization in Arabic will then be associated
with a [+
[+
though it is not clear whether [+
added as an additional feature to describe pharyngealization (see Sylak-Glassman, 2014a,
p. 136–140). The inclusion of voice quality metrics allows for pharyngealization in Arabic
to be described with [+
would be that [+
2011) is the only correlate of pharyngealization. Of course this analysis is only based on
the outcomes of this study and does not look at the patterns in the language. However,
highlighting this laryngeal activity as associated with pharyngealization in Arabic can
potentially shed light into what a ‘guttural’ quality is from a phonetic point of view and
whether it is a ‘voice quality’ in the sense of ‘timbre’ of the vowel (following Story, 2016),
a ‘darker’ or ‘heavier’ auditory quality from formant merging, or both.
4.2 Limitations
This exploratory study highlights some novel acoustic evidence in describing
pharyngealization in Arabic. However, it should be noted that only coronal voiced stops
were investigated. Our formant-based measures are congruent with those reported in
amount of distance between these consonants (on F1, F2, and Z2-Z1 values). It is not clear
whether some of the results obtained are restricted to this category of sounds or whether
they can also be extended to other coronal consonants. We expect the acoustic correlates
category of sounds, as it is associated with a tense/pressed voice quality through an
epilaryngeal constriction in general, thus we expect to obtain the same degree of high
frequency components regardless of the consonant category. An additional limitation
to our study is the use of stimuli varying in location of the pharyngealized consonants
according to syllable structure and to the surrounding sounds, i.e., other gutturals. This
to evaluate the results on such a corpus to allow for testing this particular hypothesis.
Our exploratory study did not investigate the acoustic correlates of ‘true’ pharyngeals
or uvulars as our aim was to evaluate which acoustic correlates are mostly associated
with pharyngealization to allow for an extension to other categories. Finally, our study
is acoustic in nature, and any conclusions on exact articulatory consequences should be
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic Art. 28, page 31 of 40
a combined articulatory (e.g., ultrasound, and electoglottagraphy) and advanced acoustic
data of all front and back consonants in Arabic to shed light into the laryngeal constriction
and the exact constriction location of each consonant; this will allow for a meaningful
articulatory-to-acoustic mapping.
5 Conclusion
multiple acoustic correlates in describing pharyngealization. By following the predictions
of the Laryngeal Articulator Model (Esling, 2005) and its subsequent developments
(Moisik, 2013a; Sylak-Glassman, 2014a), we showed how pharyngealization in Arabic is
associated with a ‘retracted’ production, with a combined back and down gesture through
correlates obtained at each of onset and midpoint of the vowel, including formant-based
and voice quality-based measures, it was possible to evaluate the ‘retraction,’ compaction,
and epilaryngeal constriction in our data. Formant distance measures (through
between the two dialects. In summary, the results suggest that MA is associated with a
more mid-low pharyngeal constriction and JA with an upper-mid pharyngeal constriction.
Voice quality measures from spectral slope and high frequency components correlated
well with a tense/pressed voice quality and an epilaryngeal constriction respectively.
These novel results were assessed through GLMM and exploratory random forest analyses.
‘Retraction’ (i.e., combined back and down gesture) is the primary acoustic correlate of
pharyngealization in Arabic with an epilaryngeal constriction leading to a [+
measures were used alone, a simple ‘retraction’ would be the main and only correlate to
pharyngealization. Voice quality correlates allowed for the epilaryngeal constriction to be
included. A combined articulatory and acoustic investigation of the state of the epilarynx
in Arabic pharyngeals and pharyngealization is worth pursuing in order to evaluate the
role of the epilarynx as an active ‘articulator.’ A subsequent perceptual study will shed
light into which acoustic correlates are the most prominent in identifying pharyngeals
and discrimination as presented in the current study.
Additional Files
• Appendix 1.
labphon.19.s1
• Appendix 2.
org/10.5334/labphon.19.s2
• Appendix 3.
org/10.5334/labphon.19.s3
Acknowledgements
The author would like to thank Lisa Davidson, Associate Editor of Laboratory
Phonology, Kip Wilson, Editorial Assistant of Laboratory Phonology, three anonymous
reviewers, and Ghada Khattab, Danielle Turton, Dan McCarthy, Scott Moisik, John
Esling, Bodo Winter, François Pellegrino, Thami BenKirane, the audiences of BAAP
2014, the 18th ICPhS, the 2nd Arabic Linguistics Forum, the 2nd PaPE, and the Phonetics
Al-Tamimi: Revisiting acoustic correlates of pharyngealization in
Jordanian and Moroccan Arabic
Art. 28, page 32 of 40
of this study. This work was partially supported by the French Research Ministry
o. 41, P.I. R. Carré), the French
2, P.I. F. Pellegrino), and
by three funds to attend BAAP 2014, ICPhS 2015, and PaPE 2017 conferences from
Competing Interests
The author has no competing interests to declare.
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How to cite this article: Al-Tamimi, J. 2017 Revisiting acoustic correlates of pharyngealization in Jordanian and
Moroccan Arabic: Implications for formal representations.
Laboratory Phonology: Journal of the Association for
Laboratory Phonology
8(1): 28, pp. 1–40, DOI: https://doi.org/10.5334/labphon.19
Submitted: 25 April 2016 Accepted: 20 June 2017 Published: 20 November 2017
Copyright: © 2017 The Author(s). This is an open-access article distributed under the terms of the Creative Commons
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