Constraints on the Transfer of Perceptual Learning in Accented Speech

Frank Eisner,Andrea Weber,Alissa Melinger

doi:10.3389/fpsyg.2013.00148

Abstract

The perception of speech sounds can be re-tuned through a mechanism of lexically driven perceptual learning after exposure to instances of atypical speech production. This study asked whether this re-tuning is sensitive to the position of the atypical sound within the word. We investigated perceptual learning using English voiced stop consonants, which are commonly devoiced in word-final position by Dutch learners of English. After exposure to a Dutch learner’s productions of devoiced stops in word-final position (but not in any other positions), British English (BE) listeners showed evidence of perceptual learning in a subsequent cross-modal priming task, where auditory primes with devoiced final stops (e.g., “seed”, pronounced [si:th]), facilitated recognition of visual targets with voiced final stops (e.g., SEED). In Experiment 1, this learning effect generalized to test pairs where the critical contrast was in word-initial position, e.g., auditory primes such as “town” facilitated recognition of visual targets like DOWN. Control listeners, who had not heard any stops by the speaker during exposure, showed no learning effects. The generalization to word-initial position did not occur when participants had also heard correctly voiced, word-initial stops during exposure (Experiment 2), and when the speaker was a native BE speaker who mimicked the word-final devoicing (Experiment 3). The readiness of the perceptual system to generalize a previously learned adjustment to other positions within the word thus appears to be modulated by distributional properties of the speech input, as well as by the perceived sociophonetic characteristics of the speaker. The results suggest that the transfer of pre-lexical perceptual adjustments that occur through lexically driven learning can be affected by a combination of acoustic, phonological, and sociophonetic factors.

Highlights

Laboratory experiments in spoken-language research often use highly stylized samples of speech – recorded without background noise or interference from other talkers, spoken in canonical form and free of mispronunciations, accents, changes in speaking rate, or emotional tone
This learning may be guided by a variety of cues that are present in speech, such as visual information from the face of the talker (Bertelson et al, 2003), lexical and phonotactic knowledge (Norris et al, 2003; Cutler et al, 2008), and contingencies in acoustic-phonetic cues (Idemaru and Holt, 2011)
Analysis of the lexical-decision data revealed that 71% of the devoiced /d/-final training items were labeled as words by participants in the experimental group

Summary

Introduction

Laboratory experiments in spoken-language research often use highly stylized samples of speech – recorded without background noise or interference from other talkers, spoken in canonical form and free of mispronunciations, accents, changes in speaking rate, or emotional tone. Perceptual learning allows listeners to adjust to variation in speech in a variety of difficult listening situations, including spectral and temporal degradation of the signal, accents, talker variability, and talker-idiosyncratic mispronunciations (e.g., Nygaard et al, 1994; Rosen et al, 1999; Norris et al, 2003; Bradlow and Bent, 2008; Adank and Janse, 2009). This learning may be guided by a variety of cues that are present in speech, such as visual information from the face of the talker (Bertelson et al, 2003), lexical and phonotactic knowledge (Norris et al, 2003; Cutler et al, 2008), and contingencies in acoustic-phonetic cues (Idemaru and Holt, 2011)

Methods

Results

Conclusion