Volume 125, Issue 4, April 2009
Index of content:
- SPEECH PRODUCTION 
125(2009); http://dx.doi.org/10.1121/1.3081496View Description Hide Description
Three dimensional large eddy simulations, microphone “pop” measurements, and high-speed videos of the airflow and lip opening associated with the syllable “pa” are presented. In the simulations, the mouth is represented by a narrow static ellipse with a back pressure dropping to of its initial value within of the release. The simulations show a jet penetration rate that falls within range of the pressure front of microphone pop. The simulations and high-speed video experiments were within 20% agreement after , with the video experiments showing a slower penetration rate than the simulations during the first . Kinematic measurements indicate that rapid changes in lip geometry during the first underlie this discrepancy. These findings will be useful for microphone manufacturers, sound engineers, and researchers in speech aerodynamics modeling and articulatory speech synthesis.
125(2009); http://dx.doi.org/10.1121/1.3086276View Description Hide Description
This study aimed to measure solid and liquid component parameters for canine vocal fold lamina propria tissue, as is consistent with the solid and liquid fraction parameters in the context of the biphasic theory. A liquid-displacement apparatus was developed and utilized to estimate volumes of small samples of tissue. Accuracy was determined by calibrations with an object of known mass and density (copper). The experimental apparatus was then used to determine the volume of eight tissue samples, followed by an apparently complete dehydration of the samples, yielding the dry or solid tissue. The mass and volume fractions of the liquid component were sufficiently higher than those of the solid component. These results represent preliminary experimental evidence for the biphasic composition (solid-liquid) of canine lamina propria tissue as predicted in the biphasic theory. This study presents an effective experimental method to estimate some of the biphasic model parameters, and may provide a valuable application in exploring the viscoelastic behaviors of vocal fold lamina propria tissue.
An articulatory investigation of lingual coarticulatory resistance and aggressiveness for consonants and vowels in Catalan125(2009); http://dx.doi.org/10.1121/1.3089222View Description Hide Description
Lingual movement data for Catalan vowel-consonant-vowel sequences reveal differences in contextual coarticulatory variability in tongue position at the middle of the consonant for and at vowel midpoint for . The velar stop /k/ exhibits a high degree of contextual variability in the horizontal dimension but not in the vertical dimension. These differences in coarticulatory sensitivity are attributed to differences in articulatory constraint, e.g., palatality and frication cause a higher degree of resistance in the consonant than laterality. A higher degree of contextual variability for dark /l/ than expected appears to be associated with speaker-dependent differences in darkness degree. Contextual variability is greater at regions not involved in closure or constriction formation, e.g., at the tongue dorsum than at the tongue front for alveolars. Coarticulatory resistance and coarticulatory aggressiveness are positively correlated: Phonetic segments, which are especially resistant to coarticulatory effects from the adjacent segments, exert maximal coarticulation on them. Consequently, highly constrained segments such as alveolopalatal consonants turn out to affect tongue position for less constrained segments such as back vowels rather than vice versa.
125(2009); http://dx.doi.org/10.1121/1.3081523View Description Hide Description
The effect of stimulus timing on vocal responses to pitch-shifted feedback was investigated in different intonation patterns during Mandarin speech production. While speaking a four-word sentence consisting of the high-level tone, where the fundamental frequency of the final word was either increased (question intonation) or slightly falling (statement intonation), pitch-shift stimuli (±100 cents, 200 ms duration) were presented at three different times (160, 240, or 340 ms) after vocal onset. Results showed that in the question intonation, response magnitudes (16 cents) were significantly reduced for the 340 ms condition compared to the 160 (26 cents) or 240 (23 cents) ms conditions. No significant differences were found, however, as a function of stimulus timing in the statement intonation. These findings demonstrate that a planned change in can cause a modulation in the reflexive response to a perturbation in voicepitch feedback and that there is a critical time period during which the response mechanisms are most sensitive to the planning process. These findings suggest an approach for the study of mechanisms involved in the timing of successive words during speech.
125(2009); http://dx.doi.org/10.1121/1.3021438View Description Hide Description
Place assimilation can lead to neutralization of segmental contrasts. It is controversial, however, to what extent such neutralizations actually happen in natural speech. This study examines: (i) the degree to which regressive place assimilations occur in word final consonants in conversational German, and (ii) whether these assimilations are perceived as neutralized by listeners. The production analysis, based on spontaneous speech, shows that complete assimilations do take place in conversational speech and that there is a clear asymmetry between coronal versus labial and dorsal segments. Furthermore, function words show a higher degree of assimilation than lexical words. Two experiments examined the effects of assimilation on perception. A forced choice reaction time perception experiment, using nasal stimuli from the corpus, examined how fast and accurately listeners identified sounds in different segmental contexts. Results indicate that (a) with equal accuracy and speed, listeners identified original and assimilated [m]s; (b) unassimilated-/m/s were identified equally well across contexts, but not unassimilated-/n/s. A free transcription experiment reproduced these findings. An acoustic analysis provides further evidence that regressive place assimilation across word boundaries can result in absolute neutralization of place contrasts in running speech. The results support models predicting asymmetries between coronal versus labial and dorsal consonants.