Nathan Wittstock

I’ve been working with PyAudio lately, on a project to synchronize sound streams across multiple devices. Nothing to say on that front yet, but I do have a nice snippet for programatically generating a tone:

```
import math
import numpy
import pyaudio
def sine(frequency, length, rate):
length = int(length * rate)
factor = float(frequency) * (math.pi * 2) / rate
return numpy.sin(numpy.arange(length) * factor)
def play_tone(stream, frequency=440, length=1, rate=44100):
chunks = []
chunks.append(sine(frequency, length, rate))
chunk = numpy.concatenate(chunks) * 0.25
stream.write(chunk.astype(numpy.float32).tostring())
if __name__ == '__main__':
p = pyaudio.PyAudio()
stream = p.open(format=pyaudio.paFloat32,
channels=1, rate=44100, output=1)
play_tone(stream)
stream.close()
p.terminate()
```

This simply generates a sine wave of a specified frequency and length, and writes it out to an already open PyAudio stream. A pleasant tone is produced. It’s not too fancy, but it beats loading a wave file from disk.