Volume 120, Issue 4, October 2006
Index of content:
- SPEECH PRODUCTION 
120(2006); http://dx.doi.org/10.1121/1.2261270View Description Hide Description
The acoustic effects of the laryngealcavity on the vocal tractresonance were investigated by using vocal tract area functions for the five Japanese vowels obtained from an adult male speaker. Transfer functions were examined with the laryngealcavity eliminated from the whole vocal tract, volume velocity distribution patterns were calculated, and susceptance matching analysis was performed between the laryngealcavity and the vocal tract excluding the laryngealcavity(vocal tract proper). It was revealed that the laryngealcavity generates one of the formants of the vocal tract, which is the fourth in the present study. At this formant, the resonance of the laryngealcavity (the wavelength resonance) induces the open-tube resonance of the vocal tract proper (the wavelength resonance). At the other formants, on the other hand, the vocal tract proper acts as a closed tube, because the laryngealcavity has only a small contribution to generating these formants and the effective closed end of the whole vocal tract is the junction between the laryngealcavity and the vocal tract proper.
120(2006); http://dx.doi.org/10.1121/1.2335428View Description Hide Description
Acoustic effects of the time-varying glottal area due to vocal fold vibration on the laryngealcavityresonance were investigated based on vocal tract area functions and acoustic analysis. The laryngealcavity consists of the vestibular and ventricular parts of the larynx, and gives rise to a regional acoustic resonance within the vocal tract, with this resonance imparting an extra formant to the vocal tractresonance pattern. Vocal tract transfer functions of the five Japanese vowels uttered by three male subjects were calculated under open- and closed-glottis conditions. The results revealed that the resonance appears at the frequency region from 3.0 to when the glottis is closed and disappears when it is open. Real spectra estimated from open- and closed-glottis periods of vowel sounds also showed the on-off pattern of the resonance within a pitch period. Furthermore, a time-domain acoustic analysis of vowels indicated that the resonance component could be observed as a pitch-synchronized rise-and-fall pattern of the bandpass amplitude. The cyclic nature of the resonance can be explained as the laryngealcavity acting as a closed tube that generates the resonance during a closed-glottis period, but damps the resonance off during an open-glottis period.
Developmental and cross-linguistic variation in the infant vowel space: The case of Canadian English and Canadian French120(2006); http://dx.doi.org/10.1121/1.2266460View Description Hide Description
This article describes the results of two experiments.Experiment 1 was a cross-sectional study designed to explore developmental and cross-linguistic variation in the vowel space of 10- to 18-month-old infants, exposed to either Canadian English or Canadian French. Acoustic parameters of the infant vowel space were described (specifically the mean and standard deviation of the first and second formant frequencies) and then used to derive the grave, acute, compact, and diffuse features of the vowel space across age. A decline in mean with age for French-learning infants and a decline in mean with age for English-learning infants was observed. A developmental expansion of the vowel space into the high-front and high-back regions was also evident. In experiment 2, the Variable Linear Articulatory Model was used to model the infant vowel space taking into consideration vocal tract size and morphology. Two simulations were performed, one with full range of movement for all articulatory paramenters, and the other for movement of jaw and lip parameters only. These simulated vowel spaces were used to aid in the interpretation of the developmental changes and cross-linguistic influences on vowel production in experiment 1.