def create_noise(length, level=4):
    """Create white noise for background"""
    noise = bytearray(length)
    adjust = 128 - int(level / 2)
    i = 0
    while i < length:
        v = random.randint(0, 256)
        noise[i] = v % level + adjust
        i += 1
    return noise
Create white noise for background