Temporal fine structure in cochlear implants: Preliminary speech perception results in Cantonese-speaking implant users

Abstract

Conclusion: Acute comparisons between continuous interleaved sampling (CIS) and a temporal fine structure (TFS) coding strategy in Cantonese-speaking cochlear implant (CI) users did not reveal any significant differences in speech perception. Performance with the unfamiliar TFS coding strategy was on a par with CIS. Benefits of extended fine structure use observed in other studies should be investigated for tonal languages. Objectives: CIS-based stimulation strategies lack an explicit representation of fine structure, which is crucial for tonal language speech perception. The aim of this study was to assess speech recognition with a TFS coding strategy in Cantonese-speaking CI users with no prior fine structure experience. Methods: The fine structure coding strategy encodes TFS on a few apical channels, while the remaining more basal channels carry CIS stimuli. Twelve MED-EL implantees and long-term CIS users participated in a study comparing recognition for Cantonese lexical tones and CHINT sentences between CIS and fine structure stimulation. Results: Mean tone identification scores in 12 subjects were 59.2% with CIS and 59.2% with fine structure stimulation using 4 TFS channels, mean scores of CHINT sentences in 8 subjects were 54.2% with CIS and 55.9% with TFS stimulation. Differences between the two strategies were not significant for any speech test. Two additional versions of TFS strategy and pulse rates were tested in six subjects. No significant differences between strategies were found.

Keywords::

• Coding strategy
• temporal pitch
• speech perception
• tonal language
• lexical tones
• selected groups

Acknowledgments

The authors wish to thank all participating subjects for their time and efforts, Prof. W.I. Wei from the Division of Otorhinolaryngology at Queen Mary Hospital in Hong Kong for his support, and Jacky Choi for scoring the speech tests. This research was funded by the C. Doppler Research Association, Vienna, Austria.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.