audio wave filter out bandpass 900-1kHz

Hi;

I want to filter the recorded audio file out of the 900-1kHz range and convert it into an impulse response. How can I do it?

Answer 1

[Deep]

You can read your audio file using the audioread function:

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

More info: audioread

To filter out the 900-1kHz range, you can use a bandstop filter. MATLAB provides the designfilt function for this purpose:

d = designfilt('bandstopiir', 'FilterOrder', 2, ...
               'HalfPowerFrequency1', 900, 'HalfPowerFrequency2', 1000, ...
               'DesignMethod', 'butter', 'SampleRate', Fs);
filtered_audio = filtfilt(d, y);

More info:

• designfilt documentation
• filtfilt documentation

Finally, you can convert the filtered audio into an impulse response using the inverse Fast Fourier Transform, provided by the ifft function:

impulse_response = ifft(filtered_audio);

More info: ifft

This impulse response might not be in a playable range, so you might want to normalize it:

impulse_response = impulse_response / max(abs(impulse_response));

Please explore the documentation links provided to understand more about the functions used.

[ting po chun]

Thank you very much! the other question is how do i plot the impulse response?

[Deep]

Sure, plotting can be done by simply using the plot function.

% Define the sample rate. You can check this in your WAV file's properties.
Fs = 44100;

% Create a time vector
t = (0:length(impulse_response)-1)/Fs;

% Plot the impulse response
plot(t, impulse_response);
xlabel('Time (s)');
ylabel('Amplitude');
title('Impulse Response');

Hope this helps! :)

[ting po chun]

Thank you so much again!