Categorical perception of lexical tones in mandarin-speaking congenital amusics.

Wan-Ting Huang,Qi Dong,Chang Liu,Yun Nan

doi:10.3389/fpsyg.2015.00829

Abstract

Previous research suggests that within Mandarin-speaking congenital amusics, only a subgroup has behavioral lexical tone perception impairments (tone agnosia), whereas the rest of amusics do not. The purpose of the current study was to investigate the categorical nature of lexical tone perception in Mandarin-speaking amusics with and without behavioral lexical tone deficits. Three groups of listeners (controls, pure amusics, and amusics with tone agnosia) participated in tone identification and discrimination tasks. Indexes of the categorical perception (CP) of a physical continuum of fundamental frequencies ranging from a rising to level tone were measured. Specifically, the stimulus durations were manipulated at 100 and 200 ms. For both stimulus durations, all groups exhibited similar categorical boundaries. The pure amusics showed sharp identification slopes and significantly peaked discrimination functions similar to those of normal controls. However, such essential characteristics for the CP of lexical tones were not observed in amusics with tone agnosia. An enlarged step-size from 20 to 35 Hz was not able to produce any discrimination peaks in tone agnosics either. The current study revealed that only amusics with tone agnosia showed a lack of categorical tone perception, while the pure amusics demonstrated typical CP of lexical tones, indicating that the deficit of pitch processing in music does not necessarily result in the deficit in the CP of lexical tones. The different performance between congenital amusics with and without tone agnosia provides a new perspective on the proposition of the relationship between music and speech perception.

Highlights

Unlike most people who can enjoy music at their leisure, approximately 4% of the population (Kalmus and Fry, 1980) suffers from lifelong problems in perceiving and producing music in the absence of brain injury (Ayotte et al, 2002)
The current study revealed that only amusics with tone agnosia showed a lack of categorical tone perception, while the pure amusics demonstrated typical categorical perception (CP) of lexical tones, indicating that the deficit of pitch processing in music does not necessarily result in the deficit in the CP of lexical tones
Slopes of Tone Identification Functions The slopes were analyzed in a Two-Way analysis of variance (ANOVA) to determine whether there were any effects on the sharpness of the category boundary, with the listener group as a between-subjects factor and stimulus duration (100 vs. 200 ms) as a within-subjects factor

Summary

Introduction

Unlike most people who can enjoy music at their leisure, approximately 4% of the population (Kalmus and Fry, 1980) suffers from lifelong problems in perceiving and producing music in the absence of brain injury (Ayotte et al, 2002) These problems cannot be explained by hearing loss, intellectual deficiencies, or lack of music exposure. Accumulating evidence suggests that amusics may have behavioral difficulties with linguistic tone processing (Patel et al, 2008; Nan et al, 2010; Tillmann et al, 2011; Liu et al, 2012; Yang et al, 2013) This condition applies to both speech intonation and lexical tones and can affect the amusics either at the group level (Jiang et al, 2012; Liu et al, 2012) or only for a subgroup of individuals. Our recent research shows that only a subgroup of amusics demonstrated deficits in lexical tone perception (Nan et al, 2010; Yang et al, 2013)

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