Perceptual compensation for differences in speaking style.

A Davi Vitela,Andrew J Lotto,Natasha Warner

doi:10.3389/fpsyg.2013.00399

Abstract

It is well-established that listeners will shift their categorization of a target vowel as a function of acoustic characteristics of a preceding carrier phrase (CP). These results have been interpreted as an example of perceptual normalization for variability resulting from differences in talker anatomy. The present study examined whether listeners would normalize for acoustic variability resulting from differences in speaking style within a single talker. Two vowel series were synthesized that varied between central and peripheral vowels (the vowels in “beat”–“bit” and “bod”–“bud”). Each member of the series was appended to one of four CPs that were spoken in either a “clear” or “reduced” speech style. Participants categorized vowels in these eight contexts. A reliable shift in categorization as a function of speaking style was obtained for three of four phrase sets. This demonstrates that phrase context effects can be obtained with a single talker. However, the directions of the obtained shifts are not reliably predicted on the basis of the speaking style of the talker. Instead, it appears that the effect is determined by an interaction of the average spectrum of the phrase with the target vowel.

Highlights

One of the central challenges for theories of speech perception has always been the infamous variability in the acoustic realization of phonemes
Separate paired-sample t-tests were conducted for CP1 and CP2 with percent of /i/ responses collapsed across all series members serving as the dependent variable and speech style serving as the independent variable
The direction of shift for CP4 complicates the explanation for these perceptual context effects

Summary

Introduction

One of the central challenges for theories of speech perception has always been the infamous variability in the acoustic realization of phonemes. It is clear that listeners must use information in the surrounding speech extrinsic to the target segment to accommodate the peculiarities of the talker (Joos, 1948; Ladefoged and Broadbent, 1957; Nearey, 1989). The importance of this extrinsic information has become even more apparent with recent demonstrations that listeners will shift their perception of vowel tokens depending on the dialect or accent of a talker (e.g., Evans and Iverson, 2004; Maye et al, 2008) or even idiosyncratic productions specific to an individual talker (Norris et al, 2003). Listeners presumably learn something about typical phonological/phonetic patterns of the talker during a preceding phrase or set of phrases and alter their perception based on these expectations

Methods

Results

Discussion

Conclusion