1. Lecture 8 Neuromorphic Hearing 1

2. Outline The ear and the cochlea Silicon Cochlea 2

3. Ear and Cochlea Cross Section 3

4. Retina Cells 4

5. Hair Cells 5

6. Outline The ear and the cochlea Silicon Cochlea 6

7. Modeling of the filtering operation The cochlea can be modeled as several 2- order filters in parallel. 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

8. Resonant low pass filter with transconductance amplifiers (I) 8

9. Second order transfer function: Generic second order transfer function: 9 Resonant low pass filter with transconductance amplifiers (II)

10. Second order filters in parallel 10 Filters are tuned with exponentially increasing time constants

11. Second order filters in cascade 11

12. 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. 12