How to join two wav files using python?

Python ships with the wave module that will do what you need. The example below works when the details of the files (mono or stereo, frame rates, etc) are the same:

import wave

infiles = ["sound_1.wav", "sound_2.wav"]
outfile = "sounds.wav"

data= []
for infile in infiles:
    w = wave.open(infile, 'rb')
    data.append( [w.getparams(), w.readframes(w.getnframes())] )
    w.close()
    
output = wave.open(outfile, 'wb')
output.setparams(data[0][0])
for i in range(len(data)):
    output.writeframes(data[i][1])
output.close()

I'm the maintainer of pydub, which is designed to make this sort of thing easy.

from pydub import AudioSegment

sound1 = AudioSegment.from_wav("/path/to/file1.wav")
sound2 = AudioSegment.from_wav("/path/to/file2.wav")

combined_sounds = sound1 + sound2
combined_sounds.export("/output/path.wav", format="wav")

note: pydub is a light wrapper around audioop. So behind the scenes, it's doing essentially what Tom10 mentioned