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

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!

[Adam]

If you don't alter the negative frequencies equally with the positive ones you will end up with a complex result when you use iift to return to the time domain.

Answer 1

[Star Strider]

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

Answer 2

[Sachin Shrestha]

Hi Sven,

Regarding your error, you could listen to the audio by simply changing the last line of the code from

soundsc(y2, Fs);

to

soundsc(real(y2), Fs);

You may proceed with your testings now.

Hope this will help. Good Luck!