Subsonic is a description of the speed of a projectile, specifically one that is moving slower than the speed of sound. This is important in the shooting world, as a round that travels below the speed of sound will not break the sound barrier meaning there is no supersonic boom. The supersonic boom sound can oftentimes be louder than the actual gun firing. If the projectile is subsonic, it is moving slower than 1,126 feet per second, and it will travel through the air silently. Firearms users who also own suppressors love subsonic ammo as the lack of sonic boom compliments the suppressed weapon perfectly, resulting in a very quiet range day. In the right setting, shooting suppressed with subsonic ammo can even be safe for your naked ears.