The doppler effect is the effect that occurs when an object has a high relative velocity to you and is creating sound. The sound waves get more frequent in the front and less frequent in the back. Which the frequency of sound waves is what causes pitch.
Thanks to @donotforgetmycode for making the base project. To make this remix I had to do a lot of performance improvements. It now runs smoothly with a lot of waves. Hopefully you can learn from my changes. :)