MATLAB: How to filtre an audio signal with low-pass filtre

audiocodefilterfir1kaiserordnotch filtersignal processing

Hey guy, I'm new on Matlab and I have no idea how can I do a low pass filtre to filtre my signal.
Here is my signal and I don't know how to remove that hight frequency from backgrond and to keep just that voice.
I would like to know the easier way to do this.
I was doing some research on google and I so a lot of complicate options, and some options with butter or filter or.. to use fdatool and so on… But I could not understand how to use them no matter how much we read about this.
And please don't give me some links from some sites or other matlab questions like an answer, I've alread read everything for nothing…
This is the why how I read and playback the sound after I've try some filtres.
[Y, Fs] = audioread('semnale_audio/semnal1.wav');
%filtred my signal some how...
 player = audioplayer(fitlered_signal, Fs);
 play(player);
So please guys, if someone could explain me how can I do this I would be very glad.

Best Answer

I cannot access your dropbox file. It would be much easier for us for you to use the ‘paperclip’ icon and upload it here instead.
Even in the absence of your file, it is easy to design your filter. Human voice frequencies are in the range of about 100 Hz to 6000 Hz, so a Chebyshev Type II filter to pass voice frequencies would be:
Fs = 44100;                                             % Sampling Frequency (Change If Different)
Fn = Fs/2;                                              % Nyquist Frequency
Wp = [150  5800]/Fn;                                    % Normalised Passband
Ws = [ 50  6100]/Fn;                                    % Normalised Stopband
Rp =  1;                                                % Passband Ripple (dB)
Rs = 30;                                                % Stopband Ripple (dB)
[n,Ws] = cheb2ord(Wp,Ws,Rp,Rs);                         % Chebyshev Type II Order
[b,a] = cheby2(n,Rs,Ws);                                % IIR Filter Coefficients
[SOS,G] = tf2sos(b,a);                                  % Convert To Second-Order-Section For Stability
figure(1)
freqz(SOS, 4096, Fs)                                    % Check Filter Performance
filt_sig = filtfilt(SOS,G, Your_Signal);
Change the appropriate passband and stopband frequencies depending on the frequency content of your signal.
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