Volume 117, Issue 2, February 2005
Index of content:
- SPEECH PRODUCTION 
117(2005); http://dx.doi.org/10.1121/1.1849933View Description Hide Description
The present study was undertaken to examine if a subject’s voice responded not only to perturbations in pitch of voice feedback but also to changes in pitch of a side tone presented congruent with voice feedback. Small magnitude brief duration perturbations in pitch of voice or tone auditory feedback were randomly introduced during sustained vowelphonations. Results demonstrated a higher rate and larger magnitude of voice responses to changes in pitch of the voice compared with a triangular-shaped tone (experiment 1) or a pure tone (experiment 2). However, response latencies did not differ across voice or tone conditions. Data suggest that subjects responded to the change in rather than harmonic frequencies of auditory feedback because voice response prevalence, magnitude, or latency did not statistically differ across triangular-shaped tone or pure-tone feedback. Results indicate the audio–vocal system is sensitive to the change in pitch of a variety of sounds, which may represent a flexible system capable of adapting to changes in the subject’s voice. However, lower prevalence and smaller responses to tone pitch-shifted signals suggest that the audio–vocal system may resist changes to the pitch of other environmental sounds when voice feedback is present.
117(2005); http://dx.doi.org/10.1121/1.1840531View Description Hide Description
This paper examines lip and jaw kinematics in the production of labial stop and fricative consonants where the duration of the oral closure/constriction is varied for linguistic purposes. The subjects were speakers of Japanese and Swedish, two languages that have a contrast between short and long consonants. Lip and jaw movements were recorded using a magnetometer system. Based on earlier work showing that the lips are moving at a high velocity at the oral closure, it was hypothesized that speakers could control closure/constriction duration by varying the position of a virtual target for the lips. According to this hypothesis, the peak vertical position of the lower lip during the oral closure/constriction should be higher for the long than for the short consonants. This would result in the lips staying in contact for a longer period. The results show that this is the case for the Japanese subjects and one Swedish subject who produced non-overlapping distributions of closure/constriction duration for the two categories. However, the peak velocity of the lower lip raising movement did not differ between the two categories. Thus if the lip movements in speech are controlled by specifying a virtual target, that control must involve variations in both the position and the timing of the target.
117(2005); http://dx.doi.org/10.1121/1.1841612View Description Hide Description
Subglottal pressure is one of the main voice control factors, controlling vocal loudness. In this investigation the effects of subglottal pressure variation on the voice source in untrained female and male voices phonating at a low, a middle, and a high fundamental frequency are analyzed. The subjects produced a series of /pae/ syllables at varied degrees of vocal loudness, attempting to keep pitch constant. Subglottal pressure was estimated from the oral pressure during the /p/ occlusion. Ten subglottal pressure values, approximately equidistantly spaced within the pressure range used, were identified, and the voice source of the vowels following these pressure values was analyzed by inverse filtering the airflow signal as captured by a Rothenberg mask. The maximum flow declination rate (MFDR) was found to increase linearly with subglottal pressure, but a given subglottal pressure produced lower values for female than for male voices. The closed quotient increased quickly with subglottal pressure at low pressures and slowly at high pressures, such that the relationship can be approximated by a power function. For a given subglottal pressure value, female voices reached lower values of closed quotient than male voices.