Vowel-internal cues to vowel quality and prominence in speech perception

This study examines how variation in F0 and intensity impacts the perception of American English vowels. Both properties vary intrinsically as a function of vowel features in the speech production literature, raising the question of the perceptual impact of each. In addition to considering listeners’ interpretation of either cue as an intrinsic property of the vowel, the possible prominence-marking function of each is considered. Two patterns of prominence strengthening in vowels, sonority expansion and hyperarticulation, are tested in light of recent findings that contextual prominence impacts vowel perception in line with these effects (i.e. a prominent vowel is expected by listeners to be realized as if it had undergone prominence strengthening). Across four vowel contrasts with different height and frontness features, listeners categorized phonetic continua with variation in formants, F0 and intensity. Results show that variation in level F0 height is interpreted as an intrinsic cue by listeners. Higher F0 cues a higher vowel, following intrinsic F0 effects in the production literature. In comparison, intensity is interpreted as a prominence-lending cue, for which effect directionality is dependent on vowel height. Higher intensity high vowels undergo perceptual re-calibration in line with (acoustic) hyperarticulation, whereas higher intensity non-high vowels undergo perceptual re-calibration in line with sonority expansion.