Volume 106, Issue 1, July 1999
Index of content:
- SPEECH PRODUCTION 
Compensation strategies for the perturbation of French [u] using a lip tube. II. Perceptual analysis106(1999); http://dx.doi.org/10.1121/1.427063View Description Hide Description
A perceptual analysis of the French vowel [u] produced by 10 speakers under normal and perturbed conditions () is presented which aims at characterizing in the perceptual domain the task of a speaker for this vowel, and, then, at understanding the strategies developed by the speakers to deal with the lip perturbation. Identification and rating tests showed that the French [u] is perceptually fairly well described in the plane, and that the parameter (all frequencies in bark) provides a good overall correlate of the “grave” feature classically used to describe the vowel [u] in all languages. This permitted reanalysis of the behavior of the speakers during the perturbation experiment. Three of them succeed in producing a good [u] in spite of the lip tube, thanks to a combination of limited changes on and but without producing the strong backward movement of the tongue, which would be necessary to keep the pattern close to the one measured in normal speech. The only speaker who strongly moved his tongue back and maintained and at low values did not produce a perceptually well-rated [u], but additional tests demonstrate that this gesture allowed him to preserve the most important phonetic features of the French [u], which is primarily a back and rounded vowel. It is concluded that speech production is clearly guided by perceptual requirements, and that the speakers have a good representation of them, even if they are not all able to meet them in perturbed conditions.
A comparison of intergestural patterns in deaf and hearing adult speakers: Implications from an acoustic analysis of disyllables106(1999); http://dx.doi.org/10.1121/1.427064View Description Hide Description
Coarticulation studies in speech of deaf individuals have so far focused on intrasyllabic patterning of various consonant–vowel sequences. In this study, both inter- and intrasyllabic patterning were examined in disyllables /ə#CVC/ and the effects of phonetic context, speaking rate, and segment type were explored. Systematic observation of and durational measurements in disyllables minimally contrasting in vocalic ([i], [u,] [ɑ]) and in consonant ([b], [d]) context, respectively, was made at selected locations in the disyllable, in order to relate inferences about articulatory adjustments with their temporal coordinates. Results indicated that intervocalic coarticulation across hearing and deaf speakers varied as a function of the phonetic composition of disyllables (b ̲b or d ̲d). The deaf speakers showed reduced intervocalic coarticulation for bilabial but not for alveolar disyllables compared to the hearing speakers. Furthermore, they showed less marked consonant influences on the schwa and stressed vowel of disyllables compared to the hearing controls. Rate effects were minimal and did not alter the coarticulatory patterns observed across hearing status. The above findings modify the conclusions drawn from previous studies and suggest that the speech of deaf and hearing speakers is guided by different gestural organization.
106(1999); http://dx.doi.org/10.1121/1.428140View Description Hide Description
The effects of variations in vocal effort corresponding to common conversation situations on spectral properties of vowels were investigated. A database in which three degrees of vocal effort were suggested to the speakers by varying the distance to their interlocutor in three steps (close—0.4 m, normal—1.5 m, and far—6 m) was recorded. The speech materials consisted of isolated French vowels, uttered by ten naive speakers in a quiet furnished room. Manual measurements of fundamental frequency frequencies, and amplitudes of the first three formants and ), and on total amplitude were carried out. The speech materials were perceptually validated in three respects: identity of the vowel, gender of the speaker, and vocal effort. Results indicated that the speech materials were appropriate for the study. Acoustic analysis showed that and were highly correlated with vocal effort and varied at rates close to 5 Hz/dB for and 3.5 Hz/dB for Statistically and did not vary significantly with vocal effort. Formant amplitudes and increased significantly; The amplitudes in the high-frequency range increased more than those in the lower part of the spectrum, revealing a change in spectral tilt. On the average, when the overall amplitude is increased by 10 dB, and are increased by 11, 12.4, and 13 dB, respectively. Using “auditory” dimensions, such as the difference, and a “spectral center of gravity” between adjacent formants for representing vowel features did not reveal a better constancy of these parameters with respect to the variations of vocal effort and speaker. Thus a global view is evoked, in which all of the aspects of the signal should be processed simultaneously.