Pitch Perception With the Temporal Limits Encoder for Cochlear Implants

The temporal-limits-encoder (TLE) strategy has been proposed to enhance the representation of temporal fine structure (TFS) in cochlear implants (CIs), which is vital for many aspects of sound perception but is typically discarded by most modern CI strategies. TLE works by computing an envelope modu...

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Bibliographic Details
Published in:IEEE transactions on neural systems and rehabilitation engineering 2022, Vol.30, p.2528-2539
Main Authors: Zhou, Huali, Kan, Alan, Yu, Guangzheng, Guo, Zhenyu, Zheng, Nengheng, Meng, Qinglin
Format: Article
Language:English
Subjects:
Acoustics
Auditory system
Cochlea
Cochlear implant
Cochlear implants
Coders
Fine structure
Frequency
Frequency modulation
Modulation
Perception
Pitch
pitch perception
Ranking
Real-time systems
Signal analysis
Task analysis
temporal fine structure
Time-domain analysis
Ultrastructure
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Summary:The temporal-limits-encoder (TLE) strategy has been proposed to enhance the representation of temporal fine structure (TFS) in cochlear implants (CIs), which is vital for many aspects of sound perception but is typically discarded by most modern CI strategies. TLE works by computing an envelope modulator that is within the temporal pitch limits of CI electric hearing. This paper examines the TFS information encoded by TLE and evaluates the salience and usefulness of this information in CI users. Two experiments were conducted to compare pitch perception performance of TLE versus the widely-used Advanced Combinational Encoder (ACE) strategy. Experiment 1 investigated whether TLE processing improved pitch discrimination compared to ACE. Experiment 2 parametrically examined the effect of changing the lower frequency limit of the TLE modulator on pitch ranking. In both experiments, F0 difference limens were measured with synthetic harmonic complex tones using an adaptive procedure. Signal analysis of the outputs of TLE and ACE strategies showed that TLE introduces important temporal pitch cues that are not available with ACE. Results showed an improvement in pitch discrimination with TLE when the acoustic input had a lower F0 frequency. No significant effect of lower frequency limit was observed for pitch ranking, though a lower limit did tend to provide better outcomes. These results suggest that the envelope modulation introduced by TLE can improve pitch perception for CI listeners.
ISSN:1534-4320
1558-0210
DOI:10.1109/TNSRE.2022.3203079