Spectrogram of Speech
An example spectrogram for recorded speech data is shown in Fig.8.10. It was generated using the Matlab code displayed in Fig.8.11. The function spectrogram is listed in §I.5. The spectrogram is computed as a sequence of FFTs of windowed data segments. The spectrogram is plotted by spectrogram using imagesc.
[y,fs,bits] = wavread('SpeechSample.wav'); soundsc(y,fs); % Let's hear it % for classic look: colormap('gray'); map = colormap; imap = flipud(map); M = round(0.02*fs); % 20 ms window is typical N = 2^nextpow2(4*M); % zero padding for interpolation w = 0.54 - 0.46 * cos(2*pi*[0:M-1]/(M-1)); % w = hamming(M); colormap(imap); % Octave wants it here spectrogram(y,N,fs,w,-M/8,1,60); colormap(imap); % Matlab wants it here title('Hi - This is <you-know-who> '); ylim([0,(fs/2)/1000]); % don't plot neg. frequencies
- The harmonics should be resolved.
- Pitch and formant variations should be closely followed.
Hann-Windowed Complex Sinusoid