| Abstract | In obstruent consonants, a major constriction in the upper vocal tract yields an increase in intraoral
pressure (Pio). Phonation requires that subglottal pressure (Psub) exceed Pio by a threshold value, so
as the transglottal pressure reaches the threshold, phonation will cease. This work investigates how
Pio 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 Pio to clarify how supraglottal
constrictions affect Pio. 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 Pio before fricative-initial sequences than stop-initial sequences, and
onset occurred at higher levels of Pio 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 Pio) 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. |