Dichotic Perception of Lexical Tones in Cantonese-Speaking Congenital Amusics.

Jing Shao,Caicai Zhang

doi:10.3389/fpsyg.2020.01411

Abstract

Congenital amusia is an inborn neurogenetic disorder of musical pitch processing, which also induces impairment in lexical tone perception. However, it has not been examined before how the brain specialization of lexical tone perception is affected in amusics. The current study adopted the dichotic listening paradigm to examine this issue, testing 18 Cantonese-speaking amusics and 18 matched controls on pitch/lexical tone identification and discrimination in three conditions: non-speech tone, low syllable variation, and high syllable variation. For typical listeners, the discrimination accuracy was higher with shorter RT in the left ear regardless of the stimulus types, suggesting a left-ear advantage in discrimination. When the demand of phonological processing increased, as in the identification task, shorter RT was still obtained in the left ear, however, the identification accuracy revealed a bilateral pattern. Taken together, the results of the identification task revealed a reduced LEA or a shift from the right hemisphere to bilateral processing in identification. Amusics exhibited overall poorer performance in both identification and discrimination tasks, indicating that pitch/lexical tone processing in dichotic listening settings was impaired, but there was no evidence that amusics showed different ear preference from controls. These findings provided temporary evidence that although amusics demonstrate deficient neural mechanisms of pitch/lexical tone processing, their ear preference patterns might not be affected. These results broadened the understanding of the nature of pitch and lexical tone processing deficiencies in amusia.

Highlights

Like impairment in language is known as “aphasia,” impairment in music perception and production is known as “amusia.” Congenital amusia is a deficit of fine-grained pitch processing, which has a negative influence on mistuned tone detection and out-of-key tone detection (Ayotte et al, 2002)
In the identification task, the identification response time (RT) was shorter in the left ear (1,822 ms for the left ear and 1,839 ms for the right ear), which might somehow suggest an left ear advantage (LEA), no lateralized difference was obtained in terms of the identification accuracy, suggesting a bilateral pattern of lexical tone processing
Our results further proved that when the tones were presented in a dichotic manner, or when the attention was intentionally directed to a target ear, amusics showed consistently degraded performance, under all the task conditions

Summary

Introduction

Like impairment in language is known as “aphasia,” impairment in music perception and production is known as “amusia.” Congenital amusia (amusia hereafter) is a deficit of fine-grained pitch processing, which has a negative influence on mistuned tone detection and out-of-key tone detection (Ayotte et al, 2002). Earlier research showed that amusia is primarily a pitch deficit (Peretz et al, 2002). This is because despite suffering from severe musical impairment in daily life, individuals with amusia. When the pitch difference was tuned to be small, a series of studies have shown that amusics performed worse than musically intact controls in processing speech intonation and emotion prosody (Jiang et al, 2010, 2012a; Liu et al, 2010; Thompson et al, 2012; Lu et al, 2015), suggesting that amusia influences speech processing negatively

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