Audio File Sounds Bad/noisy After Passing Through Low Pass Filter

I am trying to pass my audio through low pass filter, so as to filter out noise from it. However, the output of the wav is very noisy, and I am unable to understand why. Find the o

Solution 1:

Replace the line where you save the output audio with the following:

wavfile.write('LPF_filttered.wav', frq, np.int16(y/np.max(np.abs(y)) * 32767))