1. 數位信號處理專題 : 聽語資訊處理 NSL tool 相關參數介紹

2. Auditory model The auditory model was composed of early and central stages: 1. The early stage converts the sound waveform into an auditory spectrogram( 模擬人耳到中腦的部分 ) 2. The central stage performs a two dimensional wavelet transform of the auditory spectrogram( 模擬大腦解析語音 的部分 )

3. The early stage of Auditory model

4. Matlab implementation Function : loadload load colormap, filterbank and parameters such as paras 、 rv 、 sv Paras(1) : frame jump (ms)frame jump Paras(2) : time constant (ms)time constant Paras(3) : nonlinear factornonlinear factor Paras(4) : octave shiftoctave shift rv : rate vector (Hz) sv : scale vector (cyc/octave) rv 、 sv selectionrv 、 sv selection

5. Paras(1) : frame jump 時域取樣頻率 auditory spectrogram 時軸取樣頻率 paras(1):10ms 8k Hz 100 Hz Auditory model

6. The early stage (1) 範圍分佈 :~4k 共 128 個 filter (channel) 每個 filter 皆為 constant Q filter const Q : 24 channels/octave 參數 4 相關 :0 for =16K 參數 4 相關 -1 for =8K

7. The early stage (2) :HPF ，模擬將淋巴液流速 轉換成神經元發射速率的 function :sigmoid function 參數 3 相關 : 0,y=(x > 0),full compression,booleaner. 參數 3 相關 -1, y = max(x, 0), half-wave rectifier. -2, y = x, linear function :4K LPF

8. The early stage (3) One order hair cell inhibitory :envelope detector 積分器 :1K LPF 參數 2 相關 參數 2 相關 8ms 125Hz (3dB 頻寬 ) 1K Hz (LPF 頻寬 )

9. Constraint on rate 、 scale selection auditory spectrogram 時軸取樣頻率 :1000/paras(1) auditory spectrogram 頻軸取樣頻率 :24 filter/octave According to sampling theorem: max (rv) <= ½* 時軸取樣頻率 max (sv) <= ½* 頻軸取樣頻率