The purpose of this article was to determine if a semi-occluded vocal tract could be used to measure phonation threshold pressure. This is in contrast to the shutter technique, where an alternation between a fully occluded tract and an unoccluded tract is used.
Five male and 5 female volunteers phonated through a thin straw held between the lips. Oral pressure behind the lips was measured. Mathematical predictions of phonation threshold pressures were compared to the measured ones over a range of frequencies.
It was shown that, for a 2.5-mm diameter straw, phonation threshold pressures were obtainable over a 2-octave range of fundamental frequency by all volunteers. In magnitude, the pressures agreed with the 0.2-0.5 kPa values obtained in previous investigations. Sensitivity to viscoelastic and geometric properties of the vocal folds was generally not compromised with greater oral impedance, but some differences were predicted theoretically in contrast to an open mouth configuration.
Because phonation threshold pressure is always dependent on vocal tract interaction, it may be advantageous to choose an exact and fixed oral semi-occlusion for the measurement and interpret the results in light of the known acoustic load.
"Vocal exercises using semi-occluded vocal tract, such as phonating into a straw, are commonly used in voice training and therapy (Titze, 2006). The technique of phonation-intostraw is even investigated as a possible way to measure phonation threshold pressure (Titze, 2009), or to map the voice similarly to the voice range profile (Titze and Hunter, 2011). "
"This pressure change, which is particularly rapid for consonants that involve vocal-fold abduction, reduces the airflow across the glottis that fuels phonation. It may also lead to a more divergent glottal configuration and voice quality features characteristic of breathiness: Higher open quotients, more symmetrical waveshapes, and reduced vibratory amplitudes (Bickley and Stevens 1986; see also Stevens, 1991; Titze, 2009). Hence, increases in P io during obstruents may also have multiple inhibiting effects on phonation. "
[Show abstract][Hide abstract] ABSTRACT: In obstruent consonants, a major constriction in the upper vocal tract yields an increase in intraoral pressure (P(io)). Phonation requires that subglottal pressure (P(sub)) exceed P(io) by a threshold value, so as the transglottal pressure reaches the threshold, phonation will cease. This work investigates how P(io) levels at phonation offset and onset vary before and after different German voiceless obstruents (stop, fricative, affricates, clusters), and with following high vs low vowels. Articulatory contacts, measured using electropalatography, were recorded simultaneously with P(io) to clarify how supraglottal constrictions affect P(io). Effects of consonant type on phonation thresholds could be explained mainly in terms of the magnitude and timing of vocal-fold abduction. Phonation offset occurred at lower values of P(io) before fricative-initial sequences than stop-initial sequences, and onset occurred at higher levels of P(io) following the unaspirated stops of clusters compared to fricatives, affricates, and aspirated stops. The vowel effects were somewhat surprising: High vowels had an inhibitory effect at voicing offset (phonation ceasing at lower values of P(io)) in short-duration consonant sequences, but a facilitating effect on phonation onset that was consistent across consonantal contexts. The vowel influences appear to reflect a combination of vocal-fold characteristics and vocal-tract impedance.
The Journal of the Acoustical Society of America 05/2011; 129(5):3233-44. DOI:10.1121/1.3561658 · 1.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This contribution is aimed to provide material that can be used to develop more realistic physical models of voice production. The experimental methodology and the results of measurement of subglottal, oral (substitute for subglottic) and acoustic air pressure (captured at a distance of 20 cm in front of the subject's mouth) are presented. The data were measured during ordinary speech production and when the acoustic impedance and mean supraglottal resistance were raised by phonating into differently sized tubes in the air and having the other end submerged under water. The results presented in time and frequency domain show the physiological ranges and limits of the measured pressures in humans for normal and extreme phonation. Keywords: Biomechanics of voice, measurement of oral pressure, voice exercises, phonation into tubes.
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