Aging effects on categorical perception of Mandarin tones in noise

Abstract

The current study aimed at investigating the aging effect on the categorical perception of Mandarin lexical tones with varied fundamental frequency (F0) contours in noise. Mandarin tone identification and tone discrimination in quiet and noise were measured for younger and older listeners in a categorical perception paradigm where the stimuli continua varied their F0 contour systematically from the level to the rising/falling tones. Results reported that older listeners, in contrast with their younger counterparts, performed with less stimulus-tuned changes in both identification and discrimination functions and smaller peakedness in the discrimination function for both level-rising and level-falling tones. The aging effects on Mandarin tone categoricality were observed in both quiet and noise. Moreover, noise aggravated the aging effects, especially with the high SNR condition. Plus, older listeners’ identification and discrimination functions in CP paradigm positively correlated with their performance in general speech identification in noise; such correlation was not found with younger listeners. Our study suggested that older listeners had less categoricality in both identification and discrimination functions for the level-rising and level-falling tones, probably due to the aging-related decline in temporal processing.