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. 40khz is outside of the audible human range which means we cant hear it, however once the sound waves strike an object, the 40khz sound gets demodulated and you can hear the sound that'