### ASA 127th Meeting M.I.T. 1994 June 6-10

## 2aPP13. Temporal bandpass filters from simulated cochlear nucleus neurons.

**Josh Krieger
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*Speech and Natural Language Dept., Bolt Beranek and Newman, 70 Fawcett
St., Cambridge, MA 02138
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A bank of temporal bandpass filters was simulated using model cochlear
nucleus neurons. Average firing rate equations were used to model chopper
neurons as slow average rate integrators (lowpass filters with low cut-off
frequencies) and primarylike neurons as fast average rate integrators (lowpass
filters with high cut-off frequencies). Using the principle that the difference
of two lowpass filters is a bandpass filter, the filter bank was constructed so
that the output at a particular point was the difference in output rates of a
primarylike and a chopper neuron at that same point. Different bandpass shapes
were generated by varying model neuron parameters. In the linear case, only
three parameters for each chopper/primarylike pair are needed to completely
specify a simple closed-form solution for the bandwidth and center frequency of
the temporal filter. [Frisina et al., Hear. Res. 44, 99--122 (1990)] described
bandpass filterlike responses from a spectral analysis of single unit PSTH
recordings in cochlear nucleus. An explanation of this phenomena in terms of
saturation neuron firing rates was given by [Hewitt et al., J. Acoust. Soc. Am.
91, 2096--2109 (1991)]. The model presented here relies on a fundamentally
different scheme for generating bandpass filter.