hello
so if I understand right, the spectrogram should be converted to 0 and 1 only based on threshold value -40 dB ?
this is how I modified your code and the outcome of it :
[y,fs]=audioread('test_voice.wav');
fprintf("Amount of Fs is:%d \n",fs)
[yo,fo,to] = specgram(y(:,1)); % NB the amplitude of spectrogram is not in dB but in linear scale
yo = abs(yo);
figure(1),imagesc(to,fo,yo);axis('xy');
colormap jet
c=colorbar;
% apply threshold to make binary image
threshold = 0.01*max(yo,[],'all'); % equivalement in linear scale to -40 dB of max (in dB) )
spg_thres = zeros(size(yo));
ind = find(yo>threshold);
spg_thres(ind) = 1;
figure(2),imagesc(to,fo,spg_thres);axis('xy');
xlabel("Samples")
ylabel("Normalized Frequency (x pi radians/sample)")
colormap gray
c=colorbar;
