Index of content:
Volume 126, Issue 2, August 2009
- SPEECH PERCEPTION 
126(2009); http://dx.doi.org/10.1121/1.3159302View Description Hide Description
Although research has focused on the perceptual contribution of consonants to spoken syllable or word intelligibility, in sentences vowels have a distinct perceptual advantage over consonants in determining intelligibility [Kewley-Port et al., J. Acoust. Soc. Am.122, 2365–2375 (2007)]. The current study used a noise replacement paradigm to investigate how perceptual contributions of consonants and vowels are mediated by transitional information at segmental boundaries. The speech signal preserved between replacements is defined as a glimpse window. In the first experiment, glimpse windows contained proportional amounts of transitional boundary information that was either added to consonants or deleted from vowels. Results replicated a two-to-one vowel advantage for intelligibility at the traditional consonant-vowel boundary and suggest that vowel contributions remain robust against proportional deletions of the signal. The second experiment examined the combined effect of random glimpse windows not locked to segments and the distributions of durations measured from the consonant versus vowel glimpses observed in Experiment 1. Results demonstrated that, for random glimpses, the cumulative sentence duration glimpsed was an excellent predictor of performance. Comparisons across experiments confirmed that higher proportions of vowelinformation within glimpses yielded the highest sentence intelligibility.
126(2009); http://dx.doi.org/10.1121/1.3158823View Description Hide Description
The study investigated language and developmental factors in the use of visual information in audiovisual speech perception in speakers from different language backgrounds. Mandarin-Chinese and English adults and 8- to 9-year-old children were presented with /ba/, /da/, and /ga/ tokens spoken by two English and two Mandarin-Chinese speakers. A syllable identification task was presented in auditory-only, visual-only, and audiovisual (congruent and incongruent) conditions in clear and in noise. The results showed an increase in the use of visual information in adults relative to children in both the Chinese and English groups. In addition, a positive correlation between the total visual effect and speechreading performance was found, suggesting that the smaller visual influence in the bimodal condition for children might be accounted by their less sophisticated speechreading ability. In regard to the language factor, it was found that Chinese perceivers use visual information in their audiovisual speech processing to the same extent as English perceivers. Finally, there was evidence for a “non-native speaker effect” (i.e., stronger visual effect for non-native speech stimuli), but only for the English participants. Results from the current study suggest that the visual appearance of individual speakers and the acoustic-phonetic properties of specific languages should be considered in future cross-language studies.
Learning English vowels with different first-language vowel systems II: Auditory training for native Spanish and German speakersa)126(2009); http://dx.doi.org/10.1121/1.3148196View Description Hide Description
This study investigated whether individuals with small and large native-language (L1) vowel inventories learn second-language (L2) vowel systems differently, in order to better understand how L1 categories interfere with new vowel learning. Listener groups whose L1 was Spanish (5 vowels) or German (18 vowels) were given five sessions of high-variability auditory training for English vowels, after having been matched to assess their pre-test English vowel identification accuracy. Listeners were tested before and after training in terms of their identification accuracy for English vowels, the assimilation of these vowels into their L1 vowel categories, and their best exemplars for English (i.e., perceptual vowel space map). The results demonstrated that Germans improved more than Spanish speakers, despite the Germans’ more crowded L1 vowel space. A subsequent experiment demonstrated that Spanish listeners were able to improve as much as the German group after an additional ten sessions of training, and that both groups were able to retain this learning. The findings suggest that a larger vowel category inventory may facilitate new learning, and support a hypothesis that auditory training improves identification by making the application of existing categories to L2 phonemes more automatic and efficient.