MATLAB: Audio Processing

audiofilter

Can someone tell me how to use low pass filter to limit the frequency of an audio signal to <6000hz? inorder to remove higher frequency components..

Best Answer

Hi Kathik, You have left out an important bit of information and that is the sampling frequency. I'll assume that is 44.1 kHz in this example.

In what follows, Hd1 is an FIR equiripple design and H2 is an IIR Butterworth design. I'll use 50 dB of attenuation.

d = fdesign.lowpass('Fp,Fst,Ap,Ast',6000,6200,0.5,50,44100);
Hd1 = design(d);
Hd2 = design(d,'butter');

To apply the filter to data, use

    output = filter(Hd1,input);

Related Solutions

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

Déjà vu

how to design IIR highpass filter with cutoff frequency of 20Hz and FIR bandpass filter with cutoff frequency of 10Hz and 15Hz?

Make the appropriate changes to get the cascaded filter you want.

MATLAB: HOW TO DESIGN A BANDPASS FILTER

You need a lowpass filter. You can use fdesign.lowpass. There are many possible specification strings. You have not stated all your specs, like how many dB of attenuation you wish to have. I'll create an example with 50 dB and obtain both an FIR filter (Hd1) and an IIR filter(Hd2)

   d = fdesign.lowpass('Fp,Fst,Ap,Ast',1000,1200,0.5,50,1e4);
   Hd1 = design(d,'equiripple');
   Hd2 = design(d,'butter');
   t = 0:1e-4:1;
   x = cos(2*pi*500*t)+0.5*cos(2*pi*2000*t)+randn(size(t));
   out = filter(Hd1,x);
   % or out = filter(Hd2,x);

Best Answer

Related Solutions

MATLAB: How to design FIR lowpass filter with cutoff frequency, fc1 = 20 Hz and FIR bandpass filter with cutoff frequency fc2 = 10 Hz and fc3 = 35 Hz.

MATLAB: HOW TO DESIGN A BANDPASS FILTER

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