Tonal confusions in Thai listeners with sensorineural hearing loss

Abstract

In this experiment, native Thai speakers with sensorineural hearing losses identified both natural and synthetic tokens of five contrastive lexical Thai tones, traditionally labeled: mid, low, falling, high, and rising. All hearing‐impaired subjects had essentially flat losses, and were grouped by degree of hearing loss into mild‐, moderate‐, and severe‐hearing loss categories. Identification data from these subjects were compared to those obtained from normal‐hearing Thai listeners. Results indicated that the accuracy of identification decreased with severity of hearing loss in an orderly manner for both natural and synthetic tokens. However, error rates were much higher for synthetic stimuli across all subject groups. For natural tokens, tonal confusions from subjects with mild and moderate losses were similar to those from normal listeners; listeners with severe losses had a qualitatively different pattern of errors. In contrast, for synthetic tokens, tonal confusions from all hearing‐impaired subjects differed from those made by normal listeners both qualitatively and quantitatively. Results will be discussed with respect to the nature of the acoustic cues needed by hearing‐impaired listeners for intonation perception.