How to make the resolution for a spectrogram higher

Question

Freya Guo 2022-9-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1806670-how-to-make-the-resolution-for-a-spectrogram-higher

评论： Freya Guo 2022-9-27

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]);

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Mathieu NOE 2022-9-19

在 MATLAB Online 中打开

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 :

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]);

Freya Guo 2022-9-27

Thank you this has helped!

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Answer 1

Chunru 2022-9-19

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1806670-how-to-make-the-resolution-for-a-spectrogram-higher#answer_1056315

在 MATLAB Online 中打开

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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Answer 2

Apeksha Bagrecha 2022-9-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1806670-how-to-make-the-resolution-for-a-spectrogram-higher#answer_1057060

在 MATLAB Online 中打开

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)’.

https://www.mathworks.com/help/releases/R2021b/matlab/matlab_prog/create-live-scripts.html?searchHighlight=create-live-scripts&s_tid=doc_srchtitle

https://www.mathworks.com/help/releases/R2021b/matlab/matlab_prog/share-live-scripts.html?searchHighlight=share-live-scripts&s_tid=doc_srchtitle

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')