I can't get the Spectrogram to work, could anyone help please, I have attached my code?

Hi, I have recorded audio using the data acquisition toolbox and I am now wanting to analyse my results in the frequency domain with time on the y-axis.

'AvgL' is the averaged signal of the audio from the left speaker and then I have taken the FFT of it multiplied by the FFT of the original driving audio signal.

I then unwrapped the FFT ('HL') to give me the phase delay. But I am unsure how to view it in the spectrogram with the frequency against time?

Fs = 44100;

Ns = 32767; % length of audio signal

f = (0:Ns-1)*(Fs/Ns);

t = ((0:Ns-1)/Fs)*2;

xfft_L = fft(AvgL'); % FFT of the average of the recorded audio signal

dfft = fft(org_mls); % FFT of the original audio signal

HL = xfft_L./dfft; % FFT

Phi = unwrap(angle(HL)); % Phase Response

omega = 2*pi*f;

PD_L = -Phi./omega';

Could any one please help? Really appreciate it :)

Answer 1

[Cindy Solomon]

Hi Sarah,

Assuming that you want to see the spectrogram of the signal "AvgL", there is actually already a function to do this in MATLAB without you expressly having to find the FFT, etc. The doc page for this function is here, but typing:

spectrogram(AvgL)

should calculate and display this for you. Hope this helps!