Competing targets in English sibilant imitation.

This study investigates imitation of English /s/ to determine whether speakers converge toward normalized or raw acoustic targets. Participants exposed to increased spectral mean (SM) raised SM, converging toward both the raw acoustics of the model talker (who had high baseline SM) and the pattern of increased SM. However, after exposure to decreased SM, direction of shift depended on participant baseline. All participants converged to the raw acoustic values of the model talker, increasing or decreasing their own SM accordingly. These results suggest imitation is not necessarily mediated by perceptual normalization to different talkers, and raw acoustics can be the target of phonetic imitation. This has theoretical implications for the perception-production link and methodological implications for analysis of convergence studies.

Differential Cue Weighting in Mandarin Sibilant Production.

Individual talkers vary in their relative use of different cues to signal phonological contrast. Previous work provides limited and conflicting data on whether such variation is modulated by cue trading or individual differences in speech style. This paper examines differential cue weighting patterns in Mandarin sibilants as a test case for these hypotheses. Standardized Mandarin exhibits a three-way place contrast between retroflex, alveopalatal, and alveolar sibilants with individual differences in relative weighting of spectral center of gravity (COG) and the second formant of the following vowel (F2). In results from a speech production task, cue weights of COG and F2 are inversely correlated across speakers, demonstrating a trade-off relationship in cue use. These findings are consistent with a cue trading account of individual differences in contrast signaling.

Speech sounds in larger inventories are not (necessarily) less variable.

This paper reconsiders a classic claim about phonetic variability-that speech sounds in larger phonemic inventories should exhibit less within-category variability in production. Although this hypothesis is intuitive, existing literature provides limited unqualified support for the claim, further complicated by the fact that null results (like those failing to find a difference in variability between languages) often go unpublished. Even so, existing work suggests that factors contributing to extent of variability are multifaceted. While phonological contrast may affect variability patterns, inventory size alone is not a reliable predictor of variability differences. This paper reviews relevant findings in the literature, presents an additional case study, and argues for more nuanced alternatives to account for cross-linguistic differences in extent of phonetic variability.

A revised metric for calculating acoustic dispersion applied to stop inventories.

Dispersion Theory [DT; Liljencrants and Lindblom (1972). Language 12(1), 839-862] claims that acoustically dispersed vowel inventories should be typologically common. Dispersion is often quantified using triangle area between three mean vowel formant points. This approach is problematic; it ignores distributions, which affect speech perception [Clayards, Tanenhaus, Aslin, and Jacobs (2008). Cognition 108, 804-809]. This letter proposes a revised metric for calculating dispersion which incorporates covariance. As a test case, modeled vocal tract articulatory-acoustic data of stop consonants [Schwartz, Boe, Badin, and Sawallis (2012). J. Phonetics 40, 20-36] are examined. Although the revised metric does not recover DT predictions for stop inventories, it changes results, showing that dispersion results depend on metric choice, which is often overlooked. The metric can be used in any acoustic space to include information about within-category variation when calculating dispersion.