Here's a breakdown:

* Sound Waves: The rapid expansion of gases caused by the explosion of gunpowder creates a pressure wave that travels through the air. This pressure wave is what we perceive as sound.

* Shock Waves: At supersonic speeds (faster than the speed of sound), the bullet creates a cone-shaped shock wave in front of it. This is similar to the "sonic boom" produced by supersonic aircraft.

Let me know if you'd like to know more about either type of wave!