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Original research paper
Preschool speech intelligibility and
vocabulary skills predict long-term speech
and language outcomes following cochlear
implantation in early childhood
Irina Castellanos
1
, William G Kronenberger
2
, Jessica Beer
1
, Shirley C Henning
1
,
Bethany G Colson
1
, David B Pisoni
1
1
DeVault Otologic Research Laboratory, Department of Otolaryngology Head and Neck Surgery, Indiana
University School of Medicine, Indianapolis, IN, USA,
2
Riley Child and Adolescent Psychiatry Clinic,
Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA
Speech and language measures during grade school predict adolescent speech-language outcomes in
children who receive cochlear implants (CIs), but no research has examined whether speech and
language functioning at even younger ages is predictive of long-term outcomes in this population. The
purpose of this study was to examine whether early preschool measures of speech and language
performance predict speech-language functioning in long-term users of CIs. Early measures of speech
intelligibility and receptive vocabulary (obtained during preschool ages of 3–6 years) in a sample of 35
prelingually deaf, early-implanted children predicted speech perception, language, and verbal working
memory skills up to 18 years later. Age of onset of deafness and age at implantation added additional
variance to preschool speech intelligibility in predicting some long-term outcome scores, but the
relationship between preschool speech-language skills and later speech-language outcomes was not
significantly attenuated by the addition of these hearing history variables. These findings suggest that
speech and language development during the preschool years is predictive of long-term speech and
language functioning in early-implanted, prelingually deaf children. As a result, measures of speech-
language functioning at preschool ages can be used to identify and adjust interventions for very young CI
users who may be at long-term risk for suboptimal speech and language outcomes.
Keywords: Cochlear implant, Preschool measures, Long-term outcomes, Speech and language, Speech intelligibility, Receptive language
Cochlear implants (CIs) provide profoundly deaf chil-
dren with access to sound and spoken language during
a period of dynamic brain plasticity, resulting in sig-
nificant gains in speech and language skills (Niparko
et al., 2010). The FDA approved CIs as a treatment
option for deaf children with profound hearing loss
in 1990 and only recently has information about the
long-term speech and language outcomes of prelin-
gually deaf children who receive CIs during early
childhood become available. Investigation of long-
term outcomes following cochlear implantation is of
considerable importance because the effectiveness of
any treatment depends not only on short-term gains,
but also on the degree to which those gains are main-
tained over time.
Data from long-term outcome studies have demon-
strated that initial gains made in speech and language
after cochlear implantation in early childhood con-
tinue to be maintained 10–15 years later and that a
majority of these long-term CI users perform in the
average range or better on several conventional
measures of language outcomes (Davidson et al.,
2011; Geers and Hayes, 2011; Geers and Sedey,
2011; Spencer, 2004; Uziel et al., 2007). In a recent
study, users with 15–22 years of CI experience were
found to have language skills similar to users with
7–14 years of CI experience (Ruffin et al., under
review). However, very long-term CI users (15–22
years of CI use) displayed lower performance on
several measures of speech perception than other
Correspondence to: Irina Castellanos, DeVault Otologic Research
Laboratory, Department of Otolaryngology Head and Neck Surgery,
Indiana University Schoo l of Medicine, Riley Research 044, 699 Riley
Hospital Drive, Indianapolis, IN 46202, USA. Email: icastell@indiana.edu
©W.S.Maney&SonLtd2014
DOI 10.1179/1754762813Y.0000000043
Cochlear Implants International 2014 VOL. 15 NO. 4200
long-term CI users (7–14 years). These outcome differ-
ences were explained by differences between the
groups in etiology of hearing loss, pre-implant residual
hearing, age of onset of deafness, and age of implan-
tation. The very long-term CI users (15–22 years of
CI use) had more meningitic etiology, poorer pre-
implant pure-tone averages (PTAs), older age of
onset of deafness, and older age of implantation
(Ruffin et al., under review).
Although studies of long-term speech-language out-
comes following cochlear implantation in early child-
hood demonstrate positive outcomes for many users,
considerable variability still remains in speech and
language functioning in long-term CI users
(Davidson et al., 2011; Geers et al., 2011; Ruffin
et al., under review). Understanding the source of
this variability in long-term outcome and identifying
predictors offers the potential for early identification
and prevention of suboptimal speech and language
outcomes. Long-term cochlear implantation outcome
studies have shown, for example, that some conven-
tional demographic and hearing history variables
(e.g. earlier age at implantation, better pre-implant
residual hearing, non-meningitic etiology of hearing
loss, and shorter duration of deafness prior to cochlear
implantation) predict positive long-term speech and
language outcomes (Geers and Sedey, 2011; Ruffin
et al ., under review; Uziel et al., 2007). This infor-
mation has been used to guide recommendations for
treatment, as well as to identify children who might
be at high risk for suboptimal speech-language out-
comes (Copeland and Pillsbury, 2004).
Several recent longitudinal studies have also investi-
gated the potential of early speech, language, and
other neurocognitive skills to predict long-term
speech-language outcomes following cochlear implan-
tation. For example, Geers et al. (2011, 2008) exam-
ined children’s speech perception and language skills
following long-term CI use (an average of 13 years).
Measures of speech perception and language were
taken when the children entered grade school (aged
8–9 years) and then again during their high school
years. The authors report that children made signifi-
cant improvements during the grade school to high
school period in terms of increases in speech percep-
tion, word recognition, and reading, and that perform-
ance during grade school was predictive of later
long-term performance. Specifically, bette r language
and reading scores during grade school predicted
better scores during high school (Geers et al., 2011).
Additionally, measures of verbal short-term memory
in children with CIs (as indexed by digit span) pre-
dicted long-term speech and language performance
(Harris et al., 2013; Pisoni et al., 2011 ).
These studies demonstrate that behavioral measures
of speech, language, and working memory
development during the early grade school years are
predictive of long-term speech-language outcomes
into late childhood and adolescence in prelingually
deaf, early implanted children. However, little is cur-
rently known about whether speech and language
skills at even younger ages (e.g. preschool) can
predict long-term outcomes. This knowledge is criti-
cally important for several reasons: first, it will
enhance our understanding of the stability of speech
and language development following cochlear implan-
tation, and specifically whether speech-language func-
tioning is stable even back to preschool years. Second,
it will allow us to identify and treat children at-risk for
poor outcom es during a period of rapid cognitive, lin-
guistic, and social development, and third, this knowl-
edge will inform the development of early, targeted
interventions that are likely to impact long-term
speech, language, and working memory outcomes.
As the age of implantation continues to decrease,
with many deaf children now receiving unilateral
or bilateral implants prior to 24 months of age, the
preschool years are likely to be a critical time for
rapid development and early intervention in children
with CIs.
In order to address these research questions, we
investigated the relationship between speech intellig-
ibility and receptive vocabulary skills in a group of
35 deaf children during preschool ages (after at least
1 year of CI use) and a broad set of speech, language,
and verbal memory skills following long-term use (at
least 7 years of CI use). Speech intelligibility and
receptive vocabulary are a routine part of speech and
language assessments of preschool children with CIs
because of their functional importance for tracking
language development, verbal intelligence, and
quality of life (e.g. Moog and Geers, 1999). Unlike
some more complex speech and language skills (e.g.
reading, expression, language production, and com-
prehension of complex spoken language), these basic
building blocks of speech and language can be reliably
assessed at very young ages with simple behavioral
tests and are fundamental for communication and
language development (Robbins, 2003).
Children’s speech intelligibility can be examined
using assessments such as the Beginners Intelligibility
Test (BIT; Osberger et al., 1994), the McGarr
Sentence Intelligibility Test (McGarr, 1983), and the
Monsen sentences (Monsen, 1983). In these assess-
ments, children repeat short and meaningful English
sentences, and intelligibility is measured by having
small groups of normal-hearing adults transcribe the
children’s speech. Studies using these assessment
tools have shown that several hearing and device
characteristics affect children’s speech intelligibility.
Deaf children acquire better speech intelligibility if
they have better residual hearing prior to cochlear
Castellanos et al. Predicting long-term outcomes
Cochlear Implant s International 2014
VOL. 15 NO. 4 201
implantation (Svirsky et al., 2000), receive CIs earlier
in development (Peng et al., 2004; Svirsky et al.,
2007), use oral versus total communication strategies
(Svirsky et al., 2000; Tobey et al., 2003, 2011),
receive mainstream versus special education (Tobey
et al., 2003), and use multipeak, as compared to spec-
tral-peak, speech -coding strategies in their speech pro-
cessor (Peng et al., 2004). Similarly, Tobey et al. (2003)
report that additional device characteristics such as
more active electrodes and wider dynamic ranges
were predictive of better speech intelligibility in chil-
dren who had 3–7 years of CI use. These findings
underlie the important relationship between auditory
signals delivered by a CI and phonological coding
and the development of robust lexical representations
of speech.
Compared to normal-hearing children, children
with CIs have poorer speech intelligibility and show
slower improvements in their intelligibility across
development (Chin et al., 2003). The speech intellig-
ibility of children with CIs continues to improve with
development and increased device use (Chin et al.,
2003; Osberger et al., 1994; Svirsky et al., 2007;
Tobey et al., 2003, 2011). However, to date, no
research has been carried out to assess whether
measures of speech intelligibility obtained during
early development (e.g. the preschool years) are pre-
dictive of long-term speech and language functioning.
Assessments such as the Reynell Developmental
Language Scales (RDLS; Reynell and Gruber, 1990)
and Peabody Picture Vocabulary Test (PPVT; Dunn
and Dunn, 1997, 2007) have been extensively used to
examine the vocabulary and language skills of very
young children with CIs. Demographic, family
environment, and hearing history factors have all
been shown to contribute to the observed variability
in children’s language scores. Greater pre-implant
residual hearing (El-Hakim et al., 2001; Geers et al.,
2007), early age of cochlear implantation (Connor
et al., 2006; Geers et al., 2007; Hayes et al., 2009),
higher nonverbal intelligence (Geers et al., 2007),
oral versus total communication strategies (El-Hakim
et al., 2001), higher paternal education (Hayes et al.,
2009), and family environments with higher levels of
organization, but lower levels of control (Holt et al.,
2012), have all been found to be associated with deaf
children acquiring better language skills.
The receptive language skills of deaf children con-
tinue to improve following cochlear implantation
and with development. However, compared to their
normal-hearing peers, children with CIs are delayed
in acquiring new words and have smaller vocabularies
(Hayes et al., 2009). To our knowledge, only one study
has investigated whether early measures of receptive
language are predictive of long-ter m speech and
language functioning. Hay-McCutcheon et al. (2008)
examined whether language measures obtained from
children under 7 years old, who received CIs, on
average, at 4 years old, were predictive of long-term
language development. Results indicated that
measures of receptive (but not expressive) language
obtained as early as 6 months following cochlear
implantation and under 7 years of age were predictive
of core language skills in adolescence (up to 17 years
old). As children begin to receive CIs at earlier ages,
it is important to understand how performance
during these early periods of CI intervention affects
long-term functioning. It is not yet known whether
early measures of receptive language, obtained in
early implan ted children under 6 years old, are predic-
tive of long-term speech and language functioning.
Taken together, Geers
et al. (2008) and Hay-
McCutcheon et al. (2008) were the first studies to
report that early measures of children’s speech and
language are predictive of long-term performance.
To extend these findings, we investigated whether
measures obtained at even earlier ages of development
would be predictive of long-term performance in a
group of children who received CIs during a sensitive
period for language development (implanted on
average below 26 months; see Houston and
Miyamoto, 2010). We asked whether preschool
measures of speech intelligibility and receptive
language (as assessed by the BIT and the Peabody
Picture Vocabulary Test – 3, respectively) were predic-
tive of speech, language, and verbal working memory
functioning after at least 7 years of CI use (M = 11.36,
range = 7.08–19.84). Continued research in this area is
of critical importance at this time because the findings
will allow for the early identification of children who
may be at high risk for developing poor long-term out-
comes, thereby allowing for interventions to occur at
earlier stages in development in order to address not
only speech-language deficits but also the cascading
neurocognitive effects of speech-language delays
(Pisoni et al., 2010).
Methods
Participants
Study participants were drawn from a sample of 58 CI
users who volunteered to be contacted for research and
who were evaluated as a part of a larger study of long-
term outcome following cochlear implantation in
childhood (see Ruffin et al., under review, for descrip-
tive statistics on the demographics, hearing history,
speech, and language variables of the full sample).
Participants in the larger study were required to (1)
have severe-to-profound prelingual hearing loss
(>70 dB HL in the better hearing ear prior to age 3
years); (2) have received their CI prior to age 7
years; (3) have used their CI for 7 years or more; (4)
use a currently available state-of-the-art multichannel
Castellanos et al. Predicting long-term outcomes
Cochlear Implants International 2014
VOL. 15 NO. 4202
CI system; (5) live in a household with English as the
primary language; and (6) have no additional develop-
mental, neurological, or cognitive handicapping con-
ditions other than hearing loss. In order to be
include in this study, participants were also required
to have completed either the PPVT-3 or the BIT
between the ages of 3 and 6 years inclusive as a part
of a prior, related study at our CI clinic. Of the 58 par-
ticipants in the larger sample, 35 children had com-
pleted the PPVT-3 (N = 12), BIT (N = 16), or both
PPVT-3 and BIT (N = 7) during the required 3–6-
year age range, forming the sample used for analysis
in this study.
Demographic variables coded for each participant
included age, sex, family income (coded by income
ranges on a 1 (under $5500) to 10 ($95 000 and over)
scale, with values of 4, 6, and 8 corresponding to
income values of $15 000–$24 999, $35 000–$49 999,
and $65 000–$79 999, respectively), and race/ethni-
city. Additional hearing history variables included
age at onset of deafness (defined as the age at which
deafness was identified or age at the time of a known
event causing deafness), age at time of implantation,
duration between preschool and long-term follow-up
testing, duration of CI use at preschool testing, dur-
ation of CI use at long-term follow-up testing, pre-
implant residual hearing (mean unaided PTA in the
better-hearing ear for the frequencies 500, 1000, and
2000 Hz in dB HL), communication mode (coded 1
for total communication and 2 for oral communi-
cation), and etiology of deafness.
Characteristics of the study sample are summarized
in Table 1. Etiology of deafness included unknown
(N = 22), familial (at least one immediate family
member also had deafness of unknown etiology)
(N = 5), meningitis (N = 3), Mondini malformation
(N = 3), and auditory neuropathy (N = 2). On
average, children were implanted with a CI prior to
26-month old. All participants (N = 35) were fitted
with unilateral CIs prior to preschool testing and
31% (N = 11) of participants were fitted with bilateral
CIs by the time of the long-term follow-up testing. At
the time of preschool testing, participants ranged in
age from 3 to 6 years old and all had at least 1 year
Table 1 Participant demographics and hearing history
At preschool visit
At long-term follow-up visit
N
BIT
23
M (SD)
(range)
PPVT-3
19
M (SD)
(range)
All 35
M (SD)
(range)
Onset of deafness (months) 2.61 (7.01) 0.00 (0.00) 1.71 (5.78)
(0.00–25.00) (0.00–0.00) (0.00–25.00)
Age at implantation (months) 25.77 (10.16) 22.37 (10.75) 25.47 (10.77)
(9.92–43.47) (8.28–47.70) (8.28–47.70)
Age at testing (years) 3.92 (0.86) 4.10 (0.86) 13.48 (3.77)
(3.00–5.59) (3.15–5.79) (7.80–23.36)
Duration of CI use (years) 1.78 (0.76) 2.23 (0.70) 11.36 (3.40)
(1.00–3.99) (1.04–3.53) (7.08–19.84)
Pre-implant PTA* 112.44 (6.20) 108.55 (10.49) 110.67 (8.93)
(100.00–118.43) (85.00–118.43) (85.00–118.43)
Income level** NA NA 7 (2.24)
(2.00–10.00)
Count (% of sample)
Bilateral/unilateral CI
Bilateral CI 0 (0.00) 0 (0.00) 11 (0.31)
Unilateral CI 23 (1.00) 19 (1.00) 24 (0.69)
Communication mode***
Sign/total 7 (0.30) 6 (0.32) 5 (0.14)
Oral/cued 16 (0.70) 13 (0.68) 30 (0.86)
Gender
Female 10 (0.43) 8 (0.42) 14 (0.40)
Male 13 (0.57) 11 (0.58) 21 (0.60)
Race
Asian 1 (0.04) 1 (0.08) 1 (0.03)
Black 0 (0.00) 0 (0.00) 0 (0.00)
White 22 (0.96) 18 (0.92) 34 (0.97)
Ethnicity
Hispanic 0 (0.00) 1 (0.05) 1 (0.03)
Not Hispanic 23 (1.0) 18 (0.95) 34 (0.97)
*Unaided pure-tone average in the better ear for the frequencies 500, 1000, and 2000 Hz in dB HL.
**Income level (not available for the preschool visit) is coded on a scale from under $5000 (coded 1) to $95 000 and over (coded
10) with a code of 7 = $50 000–$64 999 and a code of 8 = $65 000–$79 999.
***Communication mode is coded as sign/total communication (coded 1) or oral/cued (coded 2).
CI, cochlear implant.
Castellanos et al. Predicting long-term outcomes
Cochlear Implant s International 2014
VOL. 15 NO. 4 203
of CI use. At the time of long-term follow-up testing,
participants averaged 13.48 (SD = 3.77, range =
7.80–23.36) years old and averaged 11.36 (SD =
3.40, range = 7.08–19.84) years of CI use.
Procedure
All study procedures were reviewed and approved by
the local institutional review board, and written
informed consent was obtained for all participants or
parents prior to initiation of any study procedures.
Data were obtained from research visits to a large, uni-
versity-hospital-based CI clinic conducted as a part of
two related studies: (1) a long-running, longitudinal
speech perception and production study that spanned
preschool through adolescence; and (2) a cross-sectional
long-term neurocognitive outcome study described
earlier. The long-term outcome study provided the
initial pool of 58 potential participants, for whom pre-
school visit data were sought from the longitudinal
study database. If participants were tested more than
once during preschool ages, the earliest testing session
after age 3 years and 1 year of CI use was selected for
analysis. Long-term follow-up visits took place an
average of 9.58 (SD = 3.68, range = 4.56–18.83) years
after the preschool visit. During the research visits,
licensed speech-language pathologists administered
tests of speech perception, speech production, language,
and/or working memory in the child’s preferred mode
of communication (see Oral versus Total
Communication Mode in Table 1). Speech perception
test stimuli were presented from digital recordings
over a loudspeaker at 65 dB SPL in a sound field
within a sound-treated audio booth at 0° azimuth
approximately 3 feet from the participant.
Measures
At the preschool visit, measures of speech production
(BIT) and single word receptive vocabulary (Peabody
Picture Vocabulary Test-3) were obtained to measure
components of early speech and language development.
At the long-term follow-up visit, measures of speech
perception (Hearing in Noise Test for Children and
Lexical Neighborhood Test), language (Peabody
Picture Vocabulary Test-4 and Clinical Evaluation of
Language Fundamentals), and verbal working memory
capacity (Digit Span Forward and Digit Span
Backward) were obtained to pr ovide a br oad character-
ization of long-term outcomes related to speech and
language skills. Because of ability, attention, fatigue,
or time constraints, not all children received every test
at long-term follow-up assessment; see assessment
descriptions below for group sample sizes.
Beginners Intelligibility Test (Osberger et al., 1994).
The BIT is a measure of speech intelligibility, which
requires participants to repeat a list of 10 short and
meaningful English sentences (sentences contain two
to six words) spoken live-voice by an examiner.
Audio recordings of the children’s speech were made
and played back to three normal hearing adult
judges (naïve to deaf speech), who were instructed to
transcribe each sentence. BIT scores expressed as
percent of correct words transcribed, averaged across
the three judges, were used as a measure of speech
intelligibility during preschool ages. All children who
completed the BIT during the preschool visit (N =
23) also completed all speech and language, and
verbal short-term memory assessments during the
long-term follow-up visit.
Peabody Picture Vocabulary Test – 3rd and 4th edi-
tions (PPVT-3, PPVT-4; Dunn and Dunn, 1997,
2007). The PPVT is a one-word receptive vocabulary
test, which requires participants to choose one of
four pictures matching a spoken word. For children
using total communication, Signed Exact English
accompanied the spoken word. PPVT standard
scores were used as a measure of word knowledge at
both preschool and long-term follow-up. The PPVT-
3 was given to participants during their preschool
visit and the PPVT-4 was given during the long-term
follow-up visit. Dunn and Dunn (2007) report high
correlations between scores obtained using the 3rd
and 4th editions of the PPVT. All children who
completed the PPVT-3 during the preschool visit
(N = 19) also completed the PPVT-4 during the
long-term follow-up visit.
Lexical Neighborhood Test (LNT; Kirk et al., 1995).
The LNT is an open-set test of speech perception,
which requires participants to repeat monosyllabic
words. The LNT contains 50 lexically easy (LNT-E)
and lexically hard (LNT-H) words. The percent
correct responses to LNT-E and LNT-H words were
used as measures of speech perception skills at long-
term follow-up. All children who completed the
PPVT-3 during the preschool visit (N = 19) also com-
pleted t he LNT during the long-term follow-up visit.
Hearing in Noise Test for Children (HINT-C;
Nilsson et al., 1996). The HINT-C is an open-s et sen-
tence recognition test, which requires participants to
repeat 10 sentences in quiet and 10 sentences in +5-
dB background noise. The percent of correctly
repeated words were used to assess speech perception
skills at long-term follow-up. Eighteen children com-
pleted the PPVT-3 during the preschool visit and the
HINT-C during the long-term follow-up visit.
Clinical Evaluation of Language Fundamentals
Fourth Edition (CELF-4; Semel et al., 2003). The
CELF-4 is a measure of simple and complex receptive
and expressive language skills, which assesses partici-
pants on understanding concepts and following direc-
tions, recalling sentences, formulating sentences, and
vocabulary knowledge. For children using total com-
munication, Signed Exact English accompanied
Castellanos et al. Predicting long-term outcomes
Cochlear Implants International 2014
VOL. 15 NO. 4204
spoken words. CELF-4 Core Language standard
scores were used to measure global language function-
ing at long-term follow-up. Seventeen children com-
pleted the PPVT-3 during the preschool visit and the
CELF during the long-term follow-up visit.
Digit Span. Verbal working memory capacity was
assessed using the Digit Span subtest of the Wechsler
Intelligence Scale for Children, Third Edition
(WISC-III; Wechsler, 1991) and the Visual Digit
Span subtest of the Wechsler Intelligence Scale for
Children, Fourth Edition – Integrated (WISC-IV-I;
Wechsler et al., 2004). The Digit Span subtest requires
participants to reproduce a sequence of spoken digits
presented in forward (Digit Span Forward) or back-
ward (Digit Span Backward) order, whereas the
Visual Digit Span subtest requires repetition of a
series of visually presented digits in forward order.
Hence, Digit Span Forward and Visual Digit Span
differ in presentation modality but involve the same
rote short-term verbal memory task. Digit Span
Backward, on the other hand, includes an additional
concurrent component of cognitive processing (digit
reversal) during memory; therefore, relative to Digit
Span Forward, Digit Span Backward requires
additional processing effort in the form of controlled
attention (executive control) in addition to rote
short-term memory encoding and retrieval. Scaled
scores for Digit Span Forward, Digit Span
Backward, and Visual Digit Span were used as
measures of verbal working memory capacity at
long-term follow-up. All children who completed the
PPVT-3 during the preschool visit (N = 19) also com-
pleted Visual Digit Span during the long-term follow-
up visit. Eighteen children who completed the PPVT-3
during the preschool visit also completed Digit Span
Forward and Digit Span Backward during the long-
term follow-up visit.
Data analysis
First, in order to examine the relationship between
early speech-language skills and long-term outcomes,
scores from the BIT and PPVT-3 completed at pre-
school were correlated with long-term follow-up
scores on the speech perception (LNT, HINT-C),
language (PPVT-4, CELF-4), and verbal working
memory capacity (Digit Span Forward, Digit Span
Backward, Visual Digit Span) measures. Next, in
order to evaluate the independent contribution of pre-
school speech-language scores to long-term outcome
while also accounting for demographic and hearing
history variables, hierarchical blockwise regression
analyses were conducted with each long-term follow-
up speech-language score as the criterion variable
and blocks of variables entered sequentially as
follows: Block 1 (Preschool Speech-Language
Functioning) consisted of either preschool BIT or
preschool PPVT-3 as a measure of baseline early
speech-language skills. Since preschool speech-
language skills were the focus of this research, the vari-
able from this block was retained in the regression
analysis regardless of its statistical significance.
Variables for Blocks 2 and 3 were entered using a step-
wise method in which only variables significant at the
P < 0.05 level were entered into the equation; this
method was necessary due to the large number of vari-
ables in these blocks. Block 2 (Demographic and
Hearing History) consisted of demographic and
hearing history variables: gender, age of onset of deaf-
ness, age at implantation, best unaided PTA pre-
implantation, age at long-term follow-up testing, dur-
ation of CI use at long-term follow-up testing, and
duration of time between the preschool and long-
term follow-up visits. Communication mode was not
included in these analyses because only 12 participants
used a total communication mode at preschool visit,
and only 5 participants used a total communication
mode at long-term follow-up visit.
Finally, Block 3 (Moderator Effects) consisted of
the interaction (product term) of the variables in
Block 1 (Preschool BIT or PPVT-3) and Block 2
(any demographic or hearing history variables
retained in the stepwise analyses). These regression
equations test the extent to which conventional demo-
graphic or hearing history variables might add to or
attenuate the effects of early (Preschool) speech-
language skills (BIT or PPVT-3) on later (Long-
Term Follow-Up) speech-language abilities. If the
regression coefficient of preschool BIT or PPVT-3 is
attenuated (substantially reduced) by the addition of
demographic and hearing history variables in later
blocks, the more basic demographic and hearing
history variables may be considered to account for
the relation observed between preschool and long-
term follow-up speech-language skills (for example,
in a mediating relationship; see Holmbeck, 1997).
Furthermore, a statistically significant product term
in Block 3 would demonstrate that the effect of pre-
school BIT or PPVT-3 on long-term follow-up
speech-language outcome is moderated by the demo-
graphic or hearing history variable (Holmbeck, 1997).
Results
Correlational analyses
Correlations of preschool PPVT-3 and BIT scores with
scores on the long-term follow-up speech-language
measures are summarized in Table 2. PPVT-3 scores
obtained during the preschool visit were significantly
correlated with long-term performance on PPVT-4
(r = 0. 55) and HINT-C in Noise scores (r = 0.49).
Non-significant trends were found for correlations of
preschool PPVT-3 with long-ter m follow-up CELF-
Core, HINT-C in Quiet, LNT-H, and Digit Span
Castellanos et al. Predicting long-term outcomes
Cochlear Implant s International 2014
VOL. 15 NO. 4 205
Forward. Preschool BIT scores were significantly cor-
related with long-term follow-up performance on the
PPVT-4 (r = 0.58), CELF-Core (r = 0.62), HINT-C
in Noise (r = 0.53), Digit Span Forward (r = 0.46),
and Visual Digit Span (r = 0.47) tests. Additionally,
preschool PPVT-3 and preschool BIT scores were
highly correlated (r = 0.85, P < 0.05) with each other
for the seven participants who received both assess-
ments during the preschool visit.
Regression models predicting long-term
outcomes
Table 3 displays a summary of the results of the
regression analyses using preschool BIT as a predictor
of long-term follow-up speech and language scores.
None of the preschool or long-term follow-up demo-
graphic or hearing history variables significantly
added to or attenuated the relation obtained between
preschool BIT scores long-term follow-up language
outcomes: Preschool BIT accounted for 34–39% of
the variance in long-term follow-up PPVT-4 and
CELF-Core scores. Of the long-term follow-up
speech perception scores, preschool BIT significantly
predicted only HINT-C in Noise, and this relation
remained significant (although somewhat attenuated)
following the entry of age of onset of deafness into
the regression equation predicting HINT-C in Noise
(older age of onset of deafness was found to be signifi-
cantly related to poorer HINT-C in Noise scores). The
overall equation with preschool BIT and onset age of
deafness as predictors accounted for 59% of the var-
iance in HINT-C in Noise scores at long-term
follow-up. Higher preschool BIT and earlier age of
implantation significantly predicted better perform-
ance on the other long-term follow-up speech percep-
tion scores (HINT-C in Quiet, LNT-Easy, and
LNT-Hard), accounting for 34–49% of the variance
in those scores. None of the product terms (Block 3)
were significant for these equations, indicating that
the relations between preschool BIT and long-term
follow-up speech perception scores were not moder-
ated by age of onset of deafness or age of implantation.
For verbal working memory scores at long-term
follow-up, none of the demographic or hearing
history variables added to the predictive value of pre-
school BIT in the regression equations (see Table 2 for
correlations of BIT with verbal working memory
scores; bivariate regression results for preschool BIT
predicting each verbal working memory variable are
not reported because they are equivalent to correla-
tional results).
Table 2 Correlations between preschool speech
intelligibility and receptive vocabulary and long-term speech
and language outcomes
Preschool measures
PPVT-3 BIT
Long-term follow-up outcomes
Speech perception:
HINT-C in Quiet 0.45
†
0.30
HINT-C in Noise 0.49* 0.53*
LNT-E 0.32 0.30
LNT-H 0.39
†
0.29
Language:
PPVT-4 0.55* 0.58**
CELF-Core 0.48
†
0.62**
Verbal working memory capacity:
Digit span forward 0.42
†
0.46*
Digit span backward −0.14 0.17
Visual digit span 0.15 0.47*
PPVT, Peabody Picture Vocabulary Test given during the
Preschool and the Long-term Follow-up visits; Preschool BIT,
Beginners Intelligibility Test given during the Preschool visit;
CELF Core, Clinical Evaluation of Language Fundamentals
Fourth Edition Core Language Score; HINT-C, Hearing in Noise
Test for Children (In Noise =+5dB); LNT, Lexical
Neighborhood Test – Easy Words (E), Hard Words (H).
†
P < 0.10; *P < 0.05; **P < 0.01.
Table 3 Regressions predicting long-term speech and language outcomes
Long-term follow-up speech-language
PPVT-4
N = 23
CELF-Core
N = 23
HINT-C in Quiet
N = 23
HINT-C in Noise
N = 23
LNT-Easy
N = 23
LNT-Hard
N = 23
Block 1:
Preschool BIT 0.58** 0.62** 0.30 0.53* 0.30 0.29
R
2
0.34** 0.39** 0.09 0.28* 0.09 0.09
Block 2:
Preschool BIT 0.34 0.38* 0.35* 0.33
Onset of
Deafness
−0.57**
Age at
Implantation
−0.50* −0.64** −0.51*
R
2
0.34* 0.59** 0.49** 0.34*
Note: Because we analyzed the data using a stepwise regression, only demographic and hearing history variables significant at the
P < 0.05 level were entered into the equation and displayed in this table in Block 2. Values are standardized regression coefficients.
Preschool BIT, Beginners Intelligibility Test given during the Preschool visit; PPVT-4, Peabody Picture Vocabulary Test Fourth Edition;
CELF Core, Clinical Evaluation of Language Fundamentals Fourth Edition Core Language Score; HINT-C, Hearing in Noise Test for
Children (In Noise =+5dB); LNT, Lexical Neighborhood Test – Easy Words (E), Hard Words (H).
*P < 0.05; **P < 0.01.
Castellanos et al. Predicting long-term outcomes
Cochlear Implants International 2014
VOL. 15 NO. 4206
In contrast to preschool BIT results, none of the
demographic or hearing history variables added to
the predictive value of preschool PPVT-3 scores for
any of the long-term follow-up speech, language, or
working memory variables (see Table 2 for corre-
lations of preschool PPVT-3 with speech and
language, and verbal working memory scores, which
are equivalent to bivariate regression results).
Discussion
This study demon strated that early measures of pre-
school receptive vocabulary and speech intelligibility
skills predict later speech and language outcomes in
long-term users of CIs. Receptive vocabulary (PPVT-
3) during preschool was found to be highly predictive
of long-term receptive vocabulary (PPVT-4) and
speech perception (HINT-C in Noise), on average, 9
years later. Traditional demographic and hearing
history variables did not add to this predictive
relationship in hierarchical regression analyses.
Speech intelligibility (BIT) during preschool was
even more strongly related to long-term speech and
language outcomes, significantly predicting language
(PPVT-4 and CELF-Core) and forward short-term
verbal memory capacity (Digit Span Forward and
Visual Digit Span). In the regression analysis including
age at implantation and onset of deafness (the only
two demographic/hearing history variables adding
significantly to the predictiveness of preschool speech
intelligibility for later speech and language outcomes),
speech intelligibility (BIT) during preschool also sig-
nificantly predicted long-term speech perception
(HINT-C and LNT); none of the product terms
(between preschool BIT and the demographic/
hearing history variables in Block 2) significantly pre-
dicted long-term speech perception. Thus, preschool
PPVT and preschool BIT scores predicted later
speech-language functioning, and these predictive
values were not attenuated or moderated by including
the conventional demographic and hearing history
variables that add to the relations with long-term
speech-language outcomes.
Prior research has shown strong relations between
early speech and language skills and the development
of long-term speech and language skills in samples of
children with CIs. Hay-McCutcheon et al. (2008)
reported that a measure of early receptive language
using the RDLS, obtained before 7 years of age in a
group of children who, on average, received their CIs
at 4 years of age, was predictive of complex language
functioning in adolescence. Davidson et al. (2011),
Geers et al. (2008), and Tobey et al. (2011) also
reported that measures of speech intelligibility,
speech perception, and language obtained during
grade school were predictive of speech and language
performance approximately 8–10 years later. They
examined several factors associated with the variance
of individual scores and showed that overall, speech
intelligibility, speech perception, and language skills
of children with CIs continue to improve across the
grade school to high school years.
This study extends these earlier research findings by
demonstrating relationships between speech and
language skills at even earlier ( preschool) ages and
long-term speech and language outcomes in users of
CIs for an average of over 11 years (range =
7.08–19.84 years). Our findings demonstrate that
speech intelligibility and receptive vocabulary
measures obtained from a sample of children
implanted within an early age range (8.28 –47.70
months, M = 25.47) are predictive of a comprehensive
set of speech, language, and verbal working memory
long-term outcome measures. We also accounted for
several factors that typically contribute a large
amount of predicted variance in speech and language
outcomes by selecting a homogenous sample of chil-
dren with respect to the onset of deafness (below 2
years old on average, range = 0.00–25.00 months),
age at cochlear implantation (below 26 months old
on average, range = 8.28–47.70 months), chronologi-
cal age at the time of preschool testing (3–6 years
old), and duration of CI use at time of preschool
testing (at least 1 year, range = 1.00–3.99 years). This
is the first study to document that measures of very
early speech-language functioning during the pre-
school years (3–6 years old) can be used to identify
children with CIs who are at risk for poor outcomes
or who are likely to experience positive speech-
language outcomes after many years of long-term CI
use.
In our regression analysis, relatively few of the
demographic and hearing history variables added sig-
nificantly to the variance contributed by preschool
PPVT-3 and preschool BIT in predicting long-term
speech and language outcomes. Furthermore, only
age of onset of deafness (for preschool BIT and
long-term follow-up HINT-C in Noise) and age at
implantation (for preschool BIT and long-term
follow-up HINT-C in Quiet and LNT) added to the
relationship between preschool and long-term follow-
up speech and language functioning. This finding
suggests that the predictive value of early measures
of speech-language functioning for later speech-
language functioning is minimally augmented by the
addition of conventional demographic and hearing
history variables. However, in line with previous find-
ings, a small set of hearing history variables were pre-
dictive of long-term outcomes (Nikolopoulos and
Vlastarakos, 2010; Niparko et al., 2010; Peterson
et al., 2010; Wheeler et al., 2009) even after early
speech-language performance was taken into account
in regression equations. Not surprisingly, child ren
Castellanos et al. Predicting long-term outcomes
Cochlear Implant s International 2014
VOL. 15 NO. 4 207
who were implanted earlier in childhood or who had
later onset of deafness had better word and sentence
recognition skills after an average of 11 years of CI
use (range = 7.08–19.84).
The finding that better speech intelligibility (BIT)
and receptive vocabulary (PPVT-3) skills during the
preschool ages is also predictive of verbal short-term
memory performance (Digit Span Forward and
Visual Digit Span) at long-term follow-up is a novel
finding that is consistent with prior research demon-
strating close links between speech production and
spoken word recognition and the rehearsal of phono-
logical and lexical representations in immediate
verbal memory (Pisoni et al., 2011). Several studies
have found similar links between core measures of
neurocognitive functioning (using digit span as an
index for working memory capacity) and speech and
language performance in children with CIs (Harris
et al., 2013; Pisoni et al., 2011; Pisoni and Geers,
2000), but this is the first study to demonstrate a pre-
dictive relationship between preschool speech and
language measures and later verbal short-term
memory performance.
Speech intelligibility assessments such as the BIT are
extremely useful because they not only provide infor-
mation about children’s speech production skills, but
they also provide some insights into children’s verbal
working memory and control processes. In carrying
out the BIT, children are read sentences and are
instructed to repeat sentences to the examiner, which
requires encoding, storage, and retrieval of phonologi-
cal, lexical and syntactic information. Working
memory is central to complex language processing
skills and numerous past studies have shown that chil-
dren with delays and deficits in language also have dis-
turbances in working memory (Adams and
Gathercole, 2000; Riches, 2012). Because both
speech production and language comprehension
draw on the same core foundational information pro-
cessing operations (encoding, storage, and retrieval of
phonological and lexical representations in working
memory), it is not entirely surprising that better
speech intelligibility skills were predictive of better
long-term speech and language functioning in this
sample. Speech intelligibility measures like the BIT
might, in fact, be a proxy for the speed and efficiency
of verbal working memory and may provide a global
measure of how the entire system is functioning
together in an integrated fashion. Relations have
been reported between speech intelligibility and
short-term memory dynamics: Children with CIs
who produce more intelligible speech have longer
memory spans for forward digits (Pisoni and Geers,
2000; Pisoni et al., 1999), and child ren who speak
faster display longer memory spans for forward
digits (Burkholder and Pisoni, 2003; Pisoni and
Cleary, 2003), and better word recognition (Pisoni
and Cleary, 2003). These findings suggest close links
between early auditory experience and activity-depen-
dent learning after cochlear implantation and the
long-term development of verbal working memory
skills.
Our findings that preschool speech intelligibility and
receptive vocabulary are predictive of long-term
speech and language and verbal short-term memory
performance also demonstrate that preschool assess-
ments of speech intelligibility and vocabulary skills
are clinically relevant beyond just short-term function-
ing. A viable starting point for identifying at-risk CI
users and initiating interventions to maximize long-
term adjustment should begin as early as possible
during the preschool years. Recently, we also showed
that significant developmental delays in executive
functioning also begin to emerge during the preschool
years in children with CIs (Beer et al., under review),
suggesting that long-term adjustment risks may be
identified at younger ages than previously recognized.
Auditory-oral interventions that selectively focus and
target improving the speech intelligibility of children
with CIs and that emphasize articulation and phono-
logical awareness that transfer from clinical to real-
world settings (see Ertmer and Ertmer, 1998, for
specific intervention techniques) may have long-term
as well as short-term benefits for poorly performing
children. Additionally, children’s speech intelligibility
may be assessed periodically beginning intensively in
preschool as an approach to individualize educational
programs (Ertmer, 2011).
Several limitations must be taken into account in
interpreting the results of this study. First, the
sample size was relatively small (N = 23 for the pre-
school BIT and N = 19 for the preschool PPVT-3),
placing limits on statistical power, particularly for
the regression analyses. Small sample size also affected
the ability to test relations between variables, particu-
larly the effects of communication mode, which was
highly skewed toward the auditory–oral com muni-
cation modality. Second, because of behavioral and
time constraints, both preschool assessments were
not given to every child (i.e. only 7 of 35 child ren
received both the preschool BIT and preschool
PPVT-3), thus limiting our ability to fully correlate
performance across both preschool measures.
Finally, data were obtained from only two ( preschool
and long-term follow-up) time points. Longitudinal
data with more time points may provide information
about more subtle changes in developmental trajec-
tory over time.
In summary, this study investigated the ability of
preschool speech-language measures to predict long-
term speech-language functioning in users of CIs.
Measures of receptive vocabulary (PPVT-3) and
Castellanos et al. Predicting long-term outcomes
Cochlear Implants International 2014
VOL. 15 NO. 4208
speech intelligibility (BIT) obtained during the pre-
school years were found to be predictive of long-
term speech, language, and verbal working memory
performance after 7–19 years of CI use in early-
implanted deaf children with CIs. These findings
suggest the clinical utility of very early measurements
of speech and language skills in identifying children
who may be at high risk for poor long-term speech
and language outcomes following cochlear implantation.
Acknowledgment
This research was supported by grants from the
National Institutes of Health-National Institute on
Deafness and Other Communication Disorders: R01
DC009581, R01 DC000111, and T32 DC00012.
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VOL. 15 NO. 4210
