No abstract

Stop consonant voice onset time (VOT) was examined in a typological survey of over 100 languages. Within broadly defined laryngeal categories (long-lag, short-lag, and lead voicing), VOT means were found to vary extensively. Importantly, the means for members of the same laryngeal series did not vary independently but instead were highly correlated across languages. The strong linear relations identified here cannot be reduced to previously reported ordinal relations, and provide evidence for a uniformity constraint on phonetic realization: within a language, each laryngeal specification must be realized in approximately the same way across stops of different places of articulation.

Voicing contrasts in stop consonants are expressed by a constellation of acoustic cues. This study focused on a spectral cue present at burst onset in American English labial and coronal stops. Spectral shape was examined for word-initial, prevocalic stops of all three places of articulation in a laboratory production study and a large corpus of continuous read speech. Voiceless labial and coronal stops were found to have greater energy at higher frequencies in comparison to homorganic voiced stops, a difference that could not be attributed to aspiration in the voiceless stops or modal phonation in the voiced, while no consistent effect was found for dorsal stops. This pattern was found with various methods of spectral estimation (time-averaged and multitaper spectra) and measures of spectral energy concentration (center of gravity and spectral peak) for both linear and auditorily based frequency scales. Perceptual relevance of the spectral cue was tested in laboratory and online experiments with continua created by crossing burst shape and voice onset time. A trading relation was observed such that voiceless identifications were more likely for tokens with higher frequency bursts. Goodness ratings indicated that burst spectrum influences category typicality for voiceless stops even when voice onset time is unambiguous.

AbstractThe present study investigates patterns of covariation among acoustic properties of stop consonants in a large multi-talker corpus of American English connected speech. Relations among talker means for different stops on the same dimension (between-category covariation) were considerably stronger than those for different dimensions of the same stop (within-category covariation). The existence of between-category covariation supports a uniformity principle that restricts the mapping from phonological features to phonetic targets in the sound system of each speaker. This principle was formalized with factor analysis, in which observed covariation derives from a lower-dimensional space of talker variation. Knowledge of between-category phonetic covariation could facilitate perceptual adaptation to novel talkers by providing a rational basis for generalizing idiosyncratic properties to several sounds on the basis of limited exposure.

During conversation, speakers modulate characteristics of their production to match their interlocutors’ characteristics. This behavior is known as alignment . Speakers align at many linguistic levels, including the syntactic, lexical, and phonetic levels. As a result, alignment is often treated as a unitary phenomenon, in which evidence of alignment on one feature is cast as alignment of the entire linguistic level. This experiment investigates whether alignment can occur at some levels but not others, and on some features but not others, within a given dialogue. Participants interacted with two experimenters with highly contrasting acoustic-phonetic and syntactic profiles. The experimenters each described sets of pictures using a consistent acoustic-phonetic and syntactic profile; the participants then described new pictures to each experimenter individually. Alignment was measured as the degree to which subjects matched their current listener’s speech (vs. their non-listener’s) on each of several individual acoustic-phonetic and syntactic features. Additionally, a holistic measure of phonetic alignment was assessed using 323 acoustic-phonetic features analyzed jointly in a machine learning classifier. Although participants did not align on several individual spectral-phonetic or syntactic features, they did align on individual temporal-phonetic features and as measured by the holistic acoustic-phonetic profile. Thus, alignment can simultaneously occur at some levels but not others within a given dialogue, and is not a single phenomenon but rather a constellation of loosely-related effects. These findings suggest that the mechanism underlying alignment is not a primitive, automatic priming mechanism but rather guided by communicative or social factors.