├── images ├── AGC1.png ├── AGC2.png ├── CAR.png ├── Gain.png ├── IHC.png ├── BM-OHC.png ├── CARFAC.png ├── Cochlea.png └── filter.png ├── .gitignore ├── README.md └── Cochlea.ipynb /images/AGC1.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/AGC1.png -------------------------------------------------------------------------------- /images/AGC2.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/AGC2.png -------------------------------------------------------------------------------- /images/CAR.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/CAR.png -------------------------------------------------------------------------------- /images/Gain.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/Gain.png -------------------------------------------------------------------------------- /images/IHC.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/IHC.png -------------------------------------------------------------------------------- /images/BM-OHC.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/BM-OHC.png -------------------------------------------------------------------------------- /images/CARFAC.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/CARFAC.png -------------------------------------------------------------------------------- /images/Cochlea.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/Cochlea.png -------------------------------------------------------------------------------- /images/filter.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/vschaik/CARFAC/master/images/filter.png -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | 2 | .ipynb_checkpoints/CARFAC-checkpoint.ipynb 3 | .ipynb_checkpoints/CARFACAGC-checkpoint.ipynb 4 | images/.DS_Store 5 | .DS_Store 6 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | CARFAC 2 | ====== 3 | 4 | Cochlear Modelling Jupyter Notebooks 5 | 6 | These are developed by [Andre van Schaik](https://westernsydney.edu.au/bens) based on Dick Lyons' book [Human and Machine Hearing](http://www.machinehearing.org). 7 | 8 | Start with Cochlea.ipynb, then CAR.ipynb, followed by CARFAC.ipynb and IHC.ipynb, and finally CARFACAGC.ipynb. 9 | -------------------------------------------------------------------------------- /Cochlea.ipynb: -------------------------------------------------------------------------------- 1 | { 2 | "cells": [ 3 | { 4 | "cell_type": "markdown", 5 | "metadata": {}, 6 | "source": [ 7 | "The Cochlea\n", 8 | "===\n", 9 | "\n", 10 | "This part is based on Chapter 15 of the book [Human and Machine Hearing](http://www.machinehearing.org) by Dick Lyon, which you can download for free from the author [here](https://dicklyon.com/hmh/). \n", 11 | "\n", 12 | "Notebook by André van Schaik, [International Centre for Neuromorphic Systems](https://www.westernsydney.edu.au/icns)." 13 | ] 14 | }, 15 | { 16 | "cell_type": "markdown", 17 | "metadata": {}, 18 | "source": [ 19 | "The model of the cochlea we will implement is based on the following structure:\n", 20 | "\n", 21 | "

\"Cochlea\"

\n", 22 | "\n", 23 | "This diagram, (Fig 15.1 in the book) is adapted from Dallos (1992) and elaborated, shows the functional physiological\n", 24 | "elements of one location in the cochlea, which can be seen as a pair of feedback loops. The short loop,\n", 25 | "defining the hydrodynamic wave filtering system, involves the basilar and tectorial membranes (BM–TM)\n", 26 | "and active feedback from the outer hair cells (OHC), working at audio frequencies. The longer and slower\n", 27 | "loop, the afferent/efferent loop from the inner hair cells (IHC) through the brainstem of the auditory central\n", 28 | "nervous system (CNS) and back, controls the activity level of the OHCs, automatically adapting the system to\n", 29 | "the sound level. The instantaneous wave and the slower efferent feedback interact in the OHC, the nonlinear\n", 30 | "element whose “motor” action provides gain via active undamping of the wave mechanics." 31 | ] 32 | }, 33 | { 34 | "cell_type": "markdown", 35 | "metadata": {}, 36 | "source": [ 37 | "The compressive input–output curve implemented by the CARFAC\n", 38 | "model (solid) based on the figure above is compared with the passive linear or “dead” cochlear response (dashed), to show how\n", 39 | "extra gain at low levels reduces the input level needed to reach a threshold level of mechanical response. Here\n", 40 | "the mechanical threshold is chosen to correspond to 0 dB SPL with 50 dB of gain at low level. The curve is\n", 41 | "representative of the middle of the place or CF range, as opposed to very basal and apical regions that exhibit\n", 42 | "less active gain and less compression.\n", 43 | "\n", 44 | "

\"Gain\"

\n", 45 | "\n", 46 | "The undamping provided by the Outer Hair Cells results in a 50dB improvement in hearing threshold. Without the undamping, the voice of a typical teacher at a lecture would sound as loud as that of a whisper!" 47 | ] 48 | }, 49 | { 50 | "cell_type": "markdown", 51 | "metadata": {}, 52 | "source": [ 53 | "Next, we start by modelling the Basilar Membrane in the cochlea using a cascade of filters, as shown in this notebook on [the CAR model](./CAR.ipynb)." 54 | ] 55 | } 56 | ], 57 | "metadata": { 58 | "anaconda-cloud": {}, 59 | "hide_input": false, 60 | "interpreter": { 61 | "hash": "dca0ade3e726a953b501b15e8e990130d2b7799f14cfd9f4271676035ebe5511" 62 | }, 63 | "kernelspec": { 64 | "display_name": "Python 3 (ipykernel)", 65 | "language": "python", 66 | "name": "python3" 67 | }, 68 | "language_info": { 69 | "codemirror_mode": { 70 | "name": "ipython", 71 | "version": 3 72 | }, 73 | "file_extension": ".py", 74 | "mimetype": "text/x-python", 75 | "name": "python", 76 | "nbconvert_exporter": "python", 77 | "pygments_lexer": "ipython3", 78 | "version": "3.11.6" 79 | }, 80 | "latex_envs": { 81 | "bibliofile": "biblio.bib", 82 | "cite_by": "apalike", 83 | "current_citInitial": 1, 84 | "eqLabelWithNumbers": true, 85 | "eqNumInitial": 0 86 | }, 87 | "widgets": { 88 | "state": {}, 89 | "version": "1.1.2" 90 | } 91 | }, 92 | "nbformat": 4, 93 | "nbformat_minor": 4 94 | } 95 | --------------------------------------------------------------------------------