import numpy as np
from scipy.io import wavfile


sample_rate = 8000
duration = 0.02
time = np.arange(int(sample_rate * duration)) / sample_rate

channels = np.column_stack(
    (
        0.4 * np.sin(2 * np.pi * 440 * time),
        0.4 * np.sin(2 * np.pi * 660 * time),
    )
)
source_pcm = np.round(channels * np.iinfo(np.int16).max).astype(np.int16)