Objective The purpose of the present study was to investigate Mandarin tone recognition in background noise in children with cochlear implants (CIs), and to examine the potential factors contributing to their performance. Design Tone recognition was tested using a two-alternative forced-choice paradigm in various signal-to-noise ratio (SNR) conditions (i.e., quiet, +12, +6, 0, and −6 dB). Linear correlation analysis was performed to examine possible relationships between the tone-recognition performance of the CI children and the demographic factors. Study sample Sixty-six prelingually deafened children with CIs and 52 normal-hearing (NH) children as controls participated in the study. Results Children with CIs showed overall poorer tone-recognition performance and were more susceptible to noise than their NH peers. Tone confusions between Mandarin tone 2 and tone 3 were most prominent in both CI and NH children except for in the poorest SNR conditions. Age at implantation was significantly correlated with tone-recognition performance of the CI children in noise. Conclusions There is a marked deficit in tone recognition in prelingually deafened children with CIs, particularly in noise listening conditions. While factors that contribute to the large individual differences are still elusive, early implantation could be beneficial to tone development in pediatric CI users.

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Previous studies have shown that lexical tone perception in quiet relies on the acoustic temporal fine structure (TFS) but not on the envelope (E) cues. The contributions of TFS to speech recognition in noise are under debate. In the present study, Mandarin tone tokens were mixed with speech-shaped noise (SSN) or two-talker babble (TTB) at five signal-to-noise ratios (SNRs; -18 to +6 dB). The TFS and E were then extracted from each of the 30 bands using Hilbert transform. Twenty-five combinations of TFS and E from the sound mixtures of the same tone tokens at various SNRs were created. Twenty normal-hearing, native-Mandarin-speaking listeners participated in the tone-recognition test. Results showed that tone-recognition performance improved as the SNRs in either TFS or E increased. The masking effects on tone perception for the TTB were weaker than those for the SSN. For both types of masker, the perceptual weights of TFS and E in tone perception in noise was nearly equivalent, with E playing a slightly greater role than TFS. Thus, the relative contributions of TFS and E cues to lexical tone perception in noise or in competing-talker maskers differ from those in quiet and those to speech perception of non-tonal languages.