Perception of Temporal and Spectral Information in French Vowels

Abstract

Perceptual effects of orthogonal variations in temporal and spectral information differentiating French /o/ and /o/ were examined. Although both parameters contribute to acoustic differentiation of /o/ and /o/, the phonetic and phonological structure of French suggests that duration might be a less important perceptual property in French than in languages like American English. Three 10-step /kot/-/kot/ continua were synthesized by systematically varying frequencies of the first two formants of the vowel nuclei. The three continua differed in vowel duration (140, 180, and 220 msec). Two perceptual tests, identification and 5-choice category rating, were presented to three listener groups: native French, native American English who had studied French, and native American English who did not know French. For both native American English groups, spectrally ambiguous vowels were identified and rated more often as /o/ when these vowels were long and as /o/ when short, thereby showing a trading relation between temporal and spectral information. In contrast, native French listeners showed little effect of duration in either perceptual task. Despite this perceptual insensitivity to duration, acoustic measurements showed that these French subjects' productions of /o/ and /o/ consistently maintained a duration difference. Results are interpreted to support the view that perceptual integration of the acoustic properties relevant to a phonemic contrast depends not only on covariation of the properties in the production of that contrast, but also on the prominence of this covariation in the language's phonological system.