How to make the resolution for a spectrogram higher
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I'm trying to plot the spectrogram of an auditory stimulus but the resolution looked really low. I tried to change the parameters for the plot but none helped significantly. Is there some specific parameters I can change to make a higher-quality plot? Thank you!
The code I used is as follows:
Fs=44100;
win_size = 0.01;
fft_overlap = 0.3;
hop_size = Fs*win_size;
nfft = round(hop_size/fft_overlap);
noverlap = round(nfft-hop_size);
w = sqrt(hann(nfft)); %use some window
figure
spectrogram(tWaveform, w ,noverlap, nfft, Fs, 'yaxis' );
colormap jet;
set(gca,'YLim', [0,3]);
set(gca,'XLim', [0.4,1.2]);
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1127200/image.png)
3 Comments
Mathieu NOE
on 19 Sep 2022
following my comment above , and using @Chunru demo code, you can assign a min threshold to your spectrogram plot
IMHO this makes the plot less aggressive :
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1129240/image.png)
load handel.mat
tWaveform = y;
Fs=44100;
nfft =1024;
noverlap = round(.75*nfft);
w = sqrt(hann(nfft)); %use some window
figure
spectrogram(tWaveform, w ,noverlap, nfft, Fs, 'yaxis' ,'MinThreshold',-100); % remove estimates less than -100 dB
% [S,F,T,P] = SPECTROGRAM(...,'MinThreshold',THRESH) sets the elements of
% P to zero when the corresponding elements of 10*log10(P) are less than
% THRESH. Specify THRESH in decibels. The default value of THRESH is
% -Inf.
colormap jet;
set(gca,'YLim', [0,3]);
set(gca,'XLim', [0.4,1.2]);
Accepted Answer
Chunru
on 19 Sep 2022
load handel.mat
tWaveform = y;
Fs=44100;
win_size = 0.02; % 20ms
ws = round(win_size*Fs);
noverlap = round(.75*ws);
w = sqrt(hann(ws)); %use some window
nfft =1024;
figure
spectrogram(tWaveform, w ,noverlap, nfft, Fs, 'yaxis' );
colormap jet;
set(gca,'YLim', [0,3]);
set(gca,'XLim', [0.4,1.2]);
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More Answers (1)
Apeksha Bagrecha
on 20 Sep 2022
Possible workarounds to this issue are provided below:
1) Open your script as a Live Script and export it as an HTML or other format.
You can do this by right-clicking on the script file in the Current Folder browser and selecting "Open as Live Script". Then run the script and save it to an HTML. In the save dialog box, change the ‘Save as type’ to ‘HTML (*.html)’.
2) Manually increase the resolution of the figure in your script, save the figure to an image file, and embed the image using publishing markup. e.g.
>>print('test_non_pub','-dpng','-r300')
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