MATLAB: Changing intensities (dB) of a sound file at certain frequencies

audiofftfrequency

Is there a way to parse through a sound file (in .wav format) and adjust (increase/decrease) its intensity in decibels at certain frequencies? I have tried to do FFT to get the frequency domain, then adjusting the magnitude of the soundfile by multiplying with a constant value. Then use ifft to return to the time domain.

 [y1, Fs] = audioread('sound.wav');
 Y = fft(y1);
 % decrease intensity of lower frequencies
 Y(1:1000)= Y(1:1000) .* 0.25;
 y2 = ifft(Y);
 soundsc(y2, Fs);

This does not work and gives the error : "Error using soundsc (line 25) Audio data must be real and floating point."

Here is an example of what I want to do in Matlab (0:50 – 1:20): https://youtu.be/YantpouC4Mk?t=50

Any help is appreciated, thanks in advanced!

Best Answer

See my Answer to your duplicate Question on this topic: http://www.mathworks.com/matlabcentral/answers/290073-amplify-and-dampen-certain-frequencies

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MATLAB: Spectrogram of a song

Your song may be a two-channel stereo file. Stereo files are (Nx2) matrices.

Try this:

[x(:,1),fs]=audioread('estrellita.mp3');
window=hamming(100,'periodic')
spectrogram(x,window)

then this:

[x(:,2),fs]=audioread('estrellita.mp3');
window=hamming(100,'periodic')
spectrogram(x,window)

to see what works best for you.

MATLAB: Amplify and dampen certain frequencies

There are several ways to design filters in MATLAB. What you want to do would seem to be most suitable for one of the FIR design functions, such as the Signal Processing Toolbox function firls. They allow you to define the pass-bands and stop-bands as well as the amount of attenuation you want.

Signal processing requires experimentation, so this is necessarily going to be an iterative process until you get the result you want.

My usual filter design procedure for IIR filters is here: How to design a lowpass filter for ocean wave data in Matlab? It’s not as directly applicable to your problem as firls, but contains some ideas that you will probably find helpful, especially if you are relatively new to filter design.

Best Answer

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MATLAB: Spectrogram of a song

MATLAB: Amplify and dampen certain frequencies

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