The Effects of Intrinsic Acoustic Cues on Categorical Perception in Children with Cochlear Implants

Kejuan Cheng,Xiaoxiang Chen

doi:10.5539/ijel.v10n5p110

Abstract

Many previous studies researched the influence of external cues on speech perception, yet little is known pertaining to the role of intrinsic cues in categorical perception of Mandarin vowels and tones by children with cochlear implants (CI). This study investigated the effects of intrinsic acoustic cues on categorical perception in children with CIs, compared to normal-hearing (NH) children. Categorical perception experiment paradigm was applied to evaluate their identification and discrimination abilities in perceiving /i/-/u/ with static intrinsic formants and Tone 1 (T1)-Tone 2 (T2) with dynamic intrinsic fundamental frequency (F0) contours. Results for the NH group showed that vowel continuum of /i/-/u/ was less categorically perceived than T1-T2 continuum with significantly wider boundary width and less alignment between the discrimination peak and the boundary position. However, a different categorical perception pattern was depicted for the CI group. Specifically, the CI group exhibited less categoricalness in both /i/-/u/ and T1-T2. It suggested that the effects of intrinsic acoustic cues on categorical perception was proved for the normal-hearing children, while not for the hearing-impaired children with cochlear implants. In conclusion, acoustically dynamic cues can facilitate categorical perception of speech in NH children, whereas this effect will be inhibited by difficulties in processing spectral F0 information as in the CI users.

Highlights

Categorical perception (CP) in speech sounds refers to the phenomenon that the acoustic stimuli which vary along a physical continuum of equal intervals are perceived as discrete categories, and the differences between categories are more discriminable than within categories (Harnad, 2003; Reetz & Jongman, 2009; Zhang et al, 2016)
This study investigated the effects of intrinsic acoustic cues on categorical perception in children with cochlear implants (CI), compared to normal-hearing (NH) children
Clear alignment is found in the Tone 1 (T1)-Tone 2 (T2) identification only for the NH group, while no salient peaks are found in vowels discrimination curves

Summary

Introduction

Categorical perception (CP) in speech sounds refers to the phenomenon that the acoustic stimuli which vary along a physical continuum of equal intervals are perceived as discrete categories, and the differences between categories are more discriminable than within categories (Harnad, 2003; Reetz & Jongman, 2009; Zhang et al, 2016). Categorical perception has extended from stop consonants to vowels, and to tones, and has extended from speech to non-speech. Dating back to Liberman, Harris, Hoffman and Griffith (1957), we found people perceived sounds that varied along a continuum abruptly not gradually. Liberman proposed that perception of stop consonants was “categorical”. Quite a few conclusions have been made: perception of consonants is universally believed as categorical (Liberman et al, 1957; Miller & Eimas, 1977); for contour tones, it is concluded they are categorically perceived (e.g., Abramson, 1979; Francis et al, 2003; Xu et al, 2006; Hallé et al, 2004; Peng et al, 2010 etc.), while the perception of level tones is continuous (Abramson, 1979; Francis, Ciocca, & Ng, 2003); vowels are considered as being less categorical or even continuous (Fry et al, 1962)

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Discussion

Conclusion