Ultrasonic Sound Gun (Parametric Speaker)

For this project I built a gun that shoots out a narrow beam of ultrasonic audio. The sound can only be heard by people inside the narrow beam, or through a nearby source when the audio gets demodulated. I was inspired to build this project after watching CodeParades awesome video Turning Sound Into a Laser: I definitely recommend watching his video before you watch mine. Ive seen parametric speakers for sale but I wanted to make one on my own. It works by taking an audio source, in this case a Bluetooth speaker circuit, which then gets modulated to 40khz through a 555 timer circuit. From the 555 timer the output gets amplified and then is then sent to an array of ultrasonic transducers.