def gen_tone(frequency, duration=5.0, volume=0.5, fs=44100):
    p = PyAudio()

    # Sine wave
    # samples = (np.sin(2*np.pi*np.arange(fs*duration)*frequency/fs)).astype(np.float32)

    # Sawtooth wave. Can also be done with signal.sawtooth.
    # samples = (np.modf(np.arange(fs*duration)*frequency/fs)[0]*2.0-1.0).astype(np.float32)

    # DO NOT USE Triangle wave
    # t = np.linspace(0, duration, fs*duration)
    # samples = signal.sawtooth(2 * np.pi * t * frequency, width=0.5)

    stream = p.open(format=paFloat32,
                    channels=1,
                    rate=fs,
                    output=True)

    stream.write(volume * samples)

    stream.stop_stream()
    stream.close()
    p.terminate()