• Journal of Biomedical Engineering Research
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• v.34 no.2
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• pp.47-54
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• 2013

Electrical stimulation is delivered to auditory nerve (AN) through the electrodes in cochlear implant system. Neurogram is a spectrogram that includes information of neural response to electrical stimulation. We hypothesized that the similarity between a neurogram and an input-sound spectrogram could show how well a cochlear implant system works. In this study, we evaluated electrical stimulus configuration of CIS strategy using the computational model. The computational model includes stochastic property and anatomical features of cat auditory nerve fiber. To evaluate similarity between a neurogram and an input-sound spectrogram, we calculated Structural Similarity Index (SSIM). The results show that the dynamic range and the stimulation rate per channel influenced SSIM. Finally, we suggested the optimal configuration within the given stimulus CIS. We expect that the results and the evaluating procedure could be employed to improve the performance of a cochlear implant system.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.6
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• pp.330-333
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• 2000

In this paper, a new pitch estimation method is proposed using the Robinson cochlear model. This estimation method is useful in noisy environments and especially very efficient under cochannel in which two speaker voices exist at the same time. For the one speaker speech, the pitch can be extracted from just the neurogram of the Robinson cochlear model. In this case, as the estimation is performed in time domain, the exact pitch period can be detected though the pitch period is various. But in noisy and cochannel cases, the neurogram has many spurious peaks, so we use the autocorrelators in the neurogram to manifest the period. It the autocorrelators are used for the all delays, the large amount of calculations is necessary. Due to this defect, we propose that the autocorrelators are used for the part of the delays on which energy is concentrated. First of all, the proposed algorithm is applied to the one speaker speech, and later to the cochannel speech. And then the results are compared with the autocorrelation pitch detection method.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.401-406
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• 1994

A magnetic resonance neurography technique for exclusive imaging of nerve networks is proposed. In the proposed technique, the anisotropy of diffusion coefficients of the molecules inside nerve cells was utilized to effectively suppress the magnetic resonance signal radiating from ones other than nerve tissues. Two images were obtained with diffusionweighting magnetic field gradients applied in the parallel and perpendicular directions with respect to the nerve orientation. One image was then subtract- ted from the other to form the neurogram. Experimentally obtained neurograms of the squld are presented.