Index of content:
Volume 125, Issue 6, June 2009
- SPEECH PRODUCTION 
125(2009); http://dx.doi.org/10.1121/1.3125313View Description Hide Description
In this study the acoustic and articulatory variabilities of speakers with different palate shapes were compared. Since the cross-sectional area of the vocal tract changes less for a slight change in tongue position if the palate is domeshaped than if it is flat, the acoustic variability should be greater for flat palates than for domeshaped ones. Consequently, it can be hypothesized that speakers with flat palates should reduce their articulatory variability in order to keep the acoustic output constant. This hypothesis was tested on 32 speakers recorded via electropalatography (EPG) and acoustics. The articulatory and acoustic variability of some of their vowels and /j/ was measured. Indeed, the results show that the speakers with flat palates reduce their variability in tongue height. There is no such trend in acoustic variability.
125(2009); http://dx.doi.org/10.1121/1.3123402View Description Hide Description
A number of studies have investigated acquisition of stop voicing contrast in various languages by voice onset time measurement. Korean stops, however, are all voiceless word-initially and are differentiated by multiple acoustic-phonetic parameters resulting in a three-way contrast (fortis, aspirated, and lenis). The present study examines developmental patterns of Korean word-initial stops produced by 40 Korean children aged 2;6 (year; month), 3;0, 3;6, and 4;0 years, and compare the children’s productions to those of 10 female adults. Voice onset time, fundamental frequency, and amplitude difference between the first and second harmonics of the post-stop vowel are obtained from monosyllabic near-minimal triplets at three places of articulation (labial, alveolar, and velar). Acoustic measures of children’s productions reveal both universal phoneticpatterns and phonetic variation associated with articulatory complexity specific to Korean. Language-specific fundamental frequency variation begins to emerge as early as 2;6, but appears to be mastered later than the voice onset time distinction. In comparison to the adults, young Korean children exhibit greater overlap across stop categories, and the acoustic overlap decreases over age. Results suggest that language-specific phonetic details as well as universal patterns should be examined to provide a better understanding of the speech sound development of a given language.
125(2009); http://dx.doi.org/10.1121/1.2990715View Description Hide Description
Speakers can adopt a speaking style that allows them to be understood more easily in difficult communication situations, but few studies have examined the acoustic properties of clearly produced consonants in detail. This study attempts to characterize the adaptations in the clear production of American English fricatives in a carefully controlled range of communication situations. Ten female and ten male talkers produced fricatives in vowel-fricative-vowel contexts in both a conversational and a clear style that was elicited by means of simulated recognition errors in feedback received from an interactive computer program. Acoustic measurements were taken for spectral, amplitudinal, and temporal properties known to influence fricative recognition. Results illustrate that (1) there were consistent overall style effects, several of which (consonant duration, spectral peak frequency, and spectral moments) were consistent with previous findings and a few (notably consonant-to-vowel intensity ratio) of which were not; (2) specific acoustic modifications in clear productions of fricatives were influenced by the nature of the recognition errors that prompted the productions and were consistent with efforts to emphasize potentially misperceived contrasts both within the English fricative inventory and based on feedback from the simulated listener; and (3) talkers differed widely in the types and magnitude of all modifications.
125(2009); http://dx.doi.org/10.1121/1.3106131View Description Hide Description
Previous research indicates that talkers differ in phonetically relevant properties of speech, including voice-onset-time (VOT) in word-initial stop consonants; some talkers have characteristically shorter VOTs than others. Previous research also indicates that VOT is robustly affected by contextual influences, including speaking rate and place of articulation. This paper examines whether these contextual influences on VOT are themselves talker-specific. Many tokens of alveolar ∕ti∕ (experiment 1) or labial ∕pi∕ and velar ∕ki∕ (experiment 2) were elicited from talkers across a range of rates. VOT and vowel duration (a metric of rate) were measured for each token. Hierarchical linear modeling analyses showed that (1) VOT increased as rate decreased for all talkers, but the magnitude of the increase varied significantly across talkers; thus the effect of rate on VOT was talker-specific; (2) the talker-specific effect of rate was stable across a change in place of articulation; and (3) for all talkers VOTs were shorter for labial than velar stops, and there was no significant variability in the magnitude of this displacement across talkers; thus the effect of place on VOT was not talker-specific. The implications of these findings for how listeners might accommodate talker differences in VOT during speech perception are discussed.