Effects of dialect variation on speech intelligibility in noise

Abstract

Recent research has shown that listeners can classify talkers based on their regional dialect of American English (AE). The present experiment explored the effects of regional dialect variation on speech intelligibility. Participants from various AE dialects transcribed meaningful English sentences mixed with noise. The sentences were produced by male and female talkers from four different AE regional dialects. At a favorable signal-to-noise ratio (−2 dB), intelligibility of General American and Southern talkers was significantly better than Northern and Mid-Atlantic talkers, and was significantly better for the Northern than the Mid-Atlantic talkers. At a more difficult signal-to-noise ratio (−6 dB), intelligibility was equally poor for the Southern, Northern, and Mid-Atlantic talkers, but remained significantly better for the General American talkers. No effects of listener dialect were observed. Thus, speech intelligibility in noise was generally poorer for more phonologically marked dialects (e.g., North, Mid-Atlantic) than less-marked dialects (e.g., General American). However, noise had differential effects on dialect interference; intelligibility of marked dialects was graded at easier signal-to-noise ratios, but marked dialects were equally difficult to transcribe at unfavorable signal-to-noise ratios, suggesting that dialect information may be conveyed by aspects of the signal that are relatively vulnerable to perceptual disruption by noise.