def followVoice(self):
        adc = MCP3008()
        while True:
            front = adc.read(0)
            right = adc.read(1)
            left = adc.read(2)
            # tiny values are invalid => map them to 1023
            if front < 10: front = 1023;
            # motors make noise of about 150, if motor is running
            if right < 50: right = 1023;
            if left < 50: left = 1023;
            if front < 1000 and right > 1000 and left > 1000:
                self.motor.forwardRight()
            elif front > 1000 and right < 1000 and left > 1000:
                self.motor.forwardLeft()
            elif front > 1000 and right > 1000 and left < 1000:
                self.motor.forwardRight()
            elif front < 1000 and right < 1000 and left > 1000:
                # front / right
                self.motor.forwardLeft()
                time.sleep(self.motor.SEC_PER_TURN / 360.0 * 45)
            elif front < 1000 and right > 1000 and left < 1000:
                # front / left
                self.motor.forwardRight()
                time.sleep(self.motor.SEC_PER_TURN / 360.0 * 45)
            else:
                self.motor.stop()
            time.sleep(0.1)