CHANNELS = 2
RATE = 44100
class Sound(object):
    def __init__(self,balloon):
        self.t = time()
        self.freq  = self.get_freq()
        self.phase = 0
        self.p = pyaudio.PyAudio()
        self.stream = self.p.open(format=pyaudio.paFloat32,
                channels=CHANNELS,
                rate=RATE,
                output=True,
                stream_callback=self.callback)
        self.stream.start_stream()

    def callback(self,in_data, frame_count, time_info, status):
        bal = self.get_balance() #number between 1 and 0
        right = (np.sin(self.phase+2*np.pi*self.freq*(self.t+np.arange(frame_count)/float(RATE))))
        data = np.zeros((right.shape[0]*2,),np.float32)
        data[::2] = bal*right #right speaker
        data[1::2] = (1-bal)*right #left speaker
        self.t+=frame_count/float(RATE)
        return (data, pyaudio.paContinue)

data[::2] = right #right speaker
data[1::2] = right #left speaker