23 May 2005 Enhanced cochlear implant coding using multiplicative noise (Invited Paper)
Author Affiliations +
Proceedings Volume 5841, Fluctuations and Noise in Biological, Biophysical, and Biomedical Systems III; (2005) https://doi.org/10.1117/12.611413
Event: SPIE Third International Symposium on Fluctuations and Noise, 2005, Austin, Texas, United States
We have previously advocated the deliberate addition of noise to cochlear implant signals to enhance the speech comprehension of cochlear implant users. The function of the additive noise is to mimic noise sources that are present in a healthy ear (originating, for example, from Brownian motion of the hair cells and the fluctuations induced by the opening and closing of ion channels) but are largely absent in a deafened ear where the hair cells have been damaged or destroyed. The normal ear, however, also contains multiplicative noise sources that result from the quantal nature of synaptic transmission between the inner hair-cells and the cochlear nerve. These noise synaptic noise sources are also largely absent in the deafened ear. Given that previous studies suggest that additive noise can enhance information coding by sensory systems, we have investigated whether multiplicative noise also enhances coding in a model of electrical stimulation of the cochlear nerve by a cochlear implant. The model was based on leaky integrate-and-fire dynamics and modelled refractory and accommodation effects by a threshold dependency derived from the sodium-inactivation dynamics of the Frankenhauser-Huxley equations for myelinated nerves. We show that multiplicative noise leads to a fundamental change in the coding mechanism and can lead to a marked increase in the transmitted information compared with additive noise or a control condition with no noise. These results suggest that multiplicative noise in the normal auditory system might have a functional role.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert P. Morse, Robert P. Morse, Nigel G. Stocks, Nigel G. Stocks, "Enhanced cochlear implant coding using multiplicative noise (Invited Paper)", Proc. SPIE 5841, Fluctuations and Noise in Biological, Biophysical, and Biomedical Systems III, (23 May 2005); doi: 10.1117/12.611413; https://doi.org/10.1117/12.611413

Back to Top