Change the volume of a wav file in python

I wrote a library to simplify this type of thing

You can do that like so:

from pydub import AudioSegment

song = AudioSegment.from_wav("never_gonna_give_you_up.wav")

# reduce volume by 10 dB
song_10_db_quieter = song - 10

# but let's make him *very* quiet
song = song - 36

# save the output
song.export("quieter.wav", "wav")

As you can see in the comments of the question, there are several solutions, some more efficient.

The problem was immediately detected by Jan Dvorak ("the * 5 part is clipping and overflowing") and the straightforward solution was:

s = numpy.fromstring(s, numpy.int16) / 10 * 5

In this case, this solution was perfect for me, just good enough.

Thank you all folks!

This can be done with the audioop module in Python's standard library. This way, no dependencies like pydub or numpy are needed.

import wave, audioop

factor = 0.5

with wave.open('input.wav', 'rb') as wav:
    p = wav.getparams()
    with wave.open('output.wav', 'wb') as audio:
        audio.setparams(p)
        frames = wav.readframes(p.nframes)
        audio.writeframesraw( audioop.mul(frames, p.sampwidth, factor))

The code which makes sound louder plus filter low and high frequencies

from pydub import AudioSegment

audio_file = "first.mp3"

song = AudioSegment.from_mp3(audio_file)

new = song.low_pass_filter(1000)

new1 = new.high_pass_filter(1000)

# increae volume by 6 dB
song_6_db_quieter = new1 + 6

# save the output
song_6_db_quieter.export("C://Users//User//Desktop//second.mp3", "mp3")