nvwave.playWaveFile has a keword to play the wave asynchronously. However, only the playback of the wave is async. A complete call of the function still takes around 10 miliseconds for the calling threat to return.

Code snippet:

import nvwave, time

def waveTest():
	curTime = time.time()
	nvwave.playWaveFile("waves\\start.wav")
	return time.time() - curTime

waveTest()