sound processing (frequency band-pass filter)

i know how to read a wave file using

    [y,Fs] = waveread(x.wave);

and i have a good knowledge about the fast fourier in getting the frequency domain amplitudes and the magnitudes ,but in image processing, i guess it is easy to get them in sound. what i want to build is a band pass filter that catches the frequency of 44000hz of a piano note or guitar how can i build this filter ?

Please attach any concerning links or videos that explains what helps me in details

Answer 1

[Star Strider]

A frequency of 44000 Hz is far above the range of human hearing. You probably intend ‘Concert A’, or 440 Hz.

If you have the Signal Processing Toolbox, see the documentation for the designfilt function. It will easily do what you want. Be sure to use the freqz function on your final filter design to be certain it is doing what you want it to. Use the filtfilt function to do the actual filtering of your signal.