Python script for using your Leap Motion as a weird theremin. Requirements: Leap SDK, pyaudio and numpy

theremin.py

#!/usr/bin/python

import sys
import math
import pyaudio
import numpy
import Leap
from datetime import datetime

class SoundDriver(object):
	def __init__(self, rate=44100):
		self.pyaudio = pyaudio.PyAudio()
		self.rate = rate

	@staticmethod
	def sin(frequency, length, rate):
		length = int(length * rate)
		factor = float(frequency) * (math.pi * 2) / rate
		return numpy.sin(numpy.arange(length) * factor)

	def initialize(self):
		self.stream = self.pyaudio.open(
			format = pyaudio.paFloat32,
			channels = 1,
			rate = self.rate,
			output = True)
	
	def playFrequency(self, frequency, amplitude = 1, length = 1):
		chunks = []
		chunks.append(SoundDriver().sin(frequency, length, self.rate))
		chunk = numpy.concatenate(chunks) * amplitude
		self.stream.write(chunk.astype(numpy.float32).tostring())

	def close(self):
		self.stream.stop_stream()
		self.stream.close()
		self.pyaudio.terminate()

class SampleListener(Leap.Listener):
	def hook_sound_driver(self, sound_driver):
		self.sound_driver = sound_driver

	def on_init(self, controller):
		print "Initialized"
		self.prev_value = -1

	def on_connect(self, controller):
		print "Connected"

	def on_disconnect(self, controller):
		print "Disconnected"

	def on_exit(self, controller):
		print "Exited"

	def on_frame(self, controller):
		frame = controller.frame()

		if not frame.hands.empty:
			for i in range(0, len(frame.hands)):
				hand = frame.hands[i]
				y = hand.palm_position[1]

				frequency = SampleListener().yToFreq(y)
				self.sound_driver.playFrequency(frequency, 1, 0.0689)
				# self.sound_driver.playFrequency(frequency, 1, 0.00089)
				print "Hand %d height: %f - Frequency: %f" % (i, y, frequency)

	@staticmethod
	def yToFreq(y):
		yMinHeight = 40
		yMaxHeight = 700
		minFreq = 20
		maxFreq = 20000

		y -= yMinHeight
		yMaxHeight -= yMinHeight
		maxFreq -= minFreq

		frequency = minFreq + ((maxFreq*y) / yMaxHeight)
		if frequency < minFreq:
			return minFreq
		if frequency > maxFreq:
			return maxFreq

		return frequency
		# return maxFreq - frequency


def main():
	sound = SoundDriver()
	sound.initialize()

	listener = SampleListener()
	listener.hook_sound_driver(sound)

	controller = Leap.Controller()
	controller.add_listener(listener)

	print "Press Enter to quit..."
	sys.stdin.readline()

	controller.remove_listener(listener)
	sound.close()

if __name__ == "__main__":
	main()

if you replace "if not frame.hands.empty:"
by "if frame.is_valid:"
then it works