How to put an audio file through a filter made through matlab

Hi, I'm wondering how I can place a sound file through a filter that I made through Matlab. The code works, I'm just wondering how to inject the audio file through the filter itself. I believe it should be some application of the fir1 command, though I'm not sure how to impliment it fully. The code is as follows:

Fl = 300

Fh = 3400

Samples = 44100

Wc = [Fl Fh]./Samples

bbp = fir1(256, Wc, 'band');

figure(1)

plot (1:length(bbp), bbp)

figure(2)

freqz(bbp,1)

outbp = filter(bbp,1,y);

audioread('song.wav');

info = audioinfo('song.wav')

filename = 'song.wav';

[y,Fs] = audioread('song.wav');

audiowrite(filename,y,Fs);

sound(y,Fs)

And I am looking to filter song.wav with the bandpass filter I made, rather than the default fir1 command one. Thanks for the help

Answer 1

[Mathieu NOE]

hello

some corrections needed, but you were pretty close to the solution

[y,Fs] = audioread('song.wav');
Fl = 300; 
Fh = 3400; 
Wc = [Fl Fh]./Fs; 
bbp = fir1(256, Wc, 'band');
figure(1)
plot (1:length(bbp), bbp)
figure(2)
freqz(bbp,1)
outbp = filter(bbp,1,y);
audiowrite('song_filtered.wav',outbp,Fs);
sound(outbp,Fs)

[Mathieu NOE]

ooops , I made one mistake ...

the filter cut off frequencies are normalized vs Nyquist frequency which is half of sampling rate Fs

so change that line

Wc = [Fl Fh]./Fs; 

into

Wc = [Fl Fh].*(2/Fs); 

also it's good practice to pass Fs argument to freqz function, to avoid such mistakes !

freqz(bbp,1,300,Fs)

all the best