Cochlear-implant Mandarin tone recognition with a disyllabic word corpus

Area of Science:

• Speech and Hearing Science
• Audiology
• Linguistics

Background:

• Pitch is the primary cue for lexical tone discrimination, but secondary cues like loudness and duration may aid cochlear implant (CI) users.
• Existing stimulus sets often confound pitch and secondary cues, limiting research into CI users' tone perception.

Purpose of the Study:

• To develop and validate a novel disyllabic word stimulus set (Di) that independently manipulates pitch and loudness contours.
• To investigate the role of secondary cues in lexical tone recognition for CI users with degraded pitch perception.

Main Methods:

• Created a 270-word disyllabic corpus (Di) with independent variations in primary (pitch) and secondary (loudness) cues.
• Conducted a lexical tone recognition experiment comparing the Di corpus with natural monosyllabic recordings.
• Recruited 17 CI users and 8 normal-hearing (NH) listeners for the experiment.

Main Results:

• CI users exhibited poorer pitch encoding and their tone recognition was significantly affected by manipulated secondary cues in the Di corpus.
• Despite some CI users integrating multiple cues for high scores, pitch-based tone recognition remains unsatisfactory compared to NH listeners.

Conclusions:

• The Di corpus effectively isolates pitch cues, highlighting the challenges CI users face in lexical tone perception.
• This corpus can assess CI users' pitch recognition performance and evaluate Mandarin tone enhancement strategies.
• The Di corpus is publicly available for further research.