UDP sound transfer : played sound have big noise

I have searched for the reason of this noise. Finally I could detect why this happened.

Actually, This program UDP transfer did not cause packet loss.

Even if it did, the sound do not have such a serious noise.

This program sent data correctly, and there are almost no packet loss, but the "receive" method could not receive data correctly.

In server program

def udpStream(CHUNK):

    udp = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    udp.bind(("127.0.0.1", 12345))

    while True:
        soundData, addr = udp.recvfrom(CHUNK)
        frames.append(soundData)

    udp.close()

This program could data only "25%". (I checked the amount of data)

So, I tried to receive the data multiply (CHANNELS * 2)

        soundData, addr = udp.recvfrom(CHUNK * CHANNELS * 2)

This results in the sound data can be received 100% completely.

Finally, the sound recorded by one PC is played in the other PC without noise.