Stochastic resonance in temporal processing by cochlear implant listeners

Monita Chatterjee; Mark E Robert

doi:10.1117/12.499216

30 April 2003 Stochastic resonance in temporal processing by cochlear implant listeners?

Monita Chatterjee, Mark E Robert

Proceedings Volume 5110, Fluctuations and Noise in Biological, Biophysical, and Biomedical Systems; (2003) https://doi.org/10.1117/12.499216
Event: SPIE's First International Symposium on Fluctuations and Noise, 2003, Santa Fe, New Mexico, United States

Abstract

Cochlear implants (CI) provide speech information to the hearing-impaired by transmitting temporal information from specific frequency bands to corresponding regions of the tonotopically organized auditory system via electrical stimulation. We are interested in the role of applied noise in temporal coding by CI listeners. We measured sensitivity to sinusoidal amplitude modulation in adult users of the Nucleus-22 cochlear implant. The carrier was a train of current pulses presented at various amplitudes within the subject's dynamic range, driving a single electrode pair in the middle of the implanted electrode array. Consistent with previous findings, modulation sensitivity in CI listeners was positively related to carrier level. Introducing uniformly distributed, pseudorandom noise into the carrier envelope produced level-dependent effects. At high levels, modulation sensitivity decreased with increasing noise. At less sensitive low carrier levels, modulation sensitivity showed a stochastic resonance (SR) signature with increasing noise, displaying maximum sensitivity at an optimal noise level. This finding was also consistent with previous work. In a new experiment, we tested two new ways of degrading modulation sensitivity without changing carrier level: (1) by increasing modulation frequency and (2) by introducing a concurrent, fluctuating masker on another channel. Under each of these two conditions, our results show that increasing noise in the signal carrier envelope improved sensitivity in a manner consistent with SR. These results suggest that conditions that weaken modulation sensitivity strengthen the potential for SR. We speculate that the effect arises at a relatively central stage of temporal processing in the auditory system.

Citation Download Citation

Monita Chatterjee and Mark E Robert "Stochastic resonance in temporal processing by cochlear implant listeners?", Proc. SPIE 5110, Fluctuations and Noise in Biological, Biophysical, and Biomedical Systems, (30 April 2003); https://doi.org/10.1117/12.499216

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