Lecture 8

Neuromorphic Hearing

1

Outline

• The ear and the cochlea• Silicon Cochlea

2

Ear and Cochlea Cross Section

3

Retina Cells

4

Hair Cells

5

Outline

• The ear and the cochlea• Silicon Cochlea

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Modeling of the filtering operation

• The cochlea can be modeled with several 2-order filters.

• Each filter is creater cascoding several 2-order low pass filters.

• More stability and gain is achieved.• The spatial dependence of the cut-off

frequency is modeled with distributed resistors.

7

Resonant low pass filter with transconductance amplifiers (I)

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• Second order transfer function:

• Generic second order transfer function:

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Resonant low pass filter with transconductance amplifiers (II)

Second order filters in parallel

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Filters are tuned with exponentially increasing time constants

Second order filters in cascade

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12

System Implementation

A SILICON COCHLEA

Richard F. Lyon and Carver Mead, ”An Analog Electronic Cochlea”, IEEE Trans. On Acustics, Speech and Signal Processing, Vol. 36, NO. 7, July

1998.

1000 cascode filters were employed. A real emulation should use 3000.

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