A gunshot is comprised of two separate auditory events. First, if the bullet is supersonic, there will be a sharp "crack" as the bullet passes the observer. This sound is omni-directional--that is, it doesn't give a clear indication of where the shot was fired from. The sound always comes from the direction of the bullet as it passes the observer. If the shot came from in front of you and is aimed passed your position, and the bullet crosses you on your left, the snap or crack of the bullet will come from your left.
For example, when we pulled targets in the pit at boot camp, we quickly became accustomed to the snapping sound of the bullets passing over our heads.
The second part of the gunshot is the sound of the high pressure gases make when they exit the muzzle. This is heard as a loud BOOM that most relate to as a gunshot. It travels at the speed of sound, which IIRC, is about 1130 fps at sea level. And it is unidirectional in that it does tell the observer the direction it came from.
When I first started hunting, my dad decided to show me something. He had me hide behind a 40" Ponderosa Pine located about 6 feet to the side of the 200 yard target on our private range on my grandpa's property. Then he shot a couple rounds from the bench 200 yards away. The distinctive crack, followed a split second later by the characteristic BOOM were clearly separated. He did this so I knew what it sounded like to have a bullet fired in my direction, so if I was ever out hunting I would know what incoming fire sounded like. (His advice was that if I ever heard that sound I was to hit the ground, get behind something, and start screaming obscenities at the shooter's mother, and if that didn't work, return fire.)
Because the BOOM travels at the speed of sound while the bullet often surpasses the speed of sound, the BOOM follows the crack at increasing intervals the farther down range you get. A typical high powered rifle bullet can reach 1000 yards in 1.5 seconds or less pretty easily. Sound takes a little over two and a half seconds to travel the same distance, so if you were being shot at from 1000 yards away, you'd hear a crack as the bullet passed you then a BOOM from the direction of the gunshot a little over a second later.
Sound suppressors capture the escaping gases and allow them to cool and dissipate over a longer period of time. This greatly reduces the BOOM, even if supersonic ammunition is used. This means that if someone shoots at you with a suppressed high powered rifle, all you hear is the crack, which gives no indication of where the shot came from. It tells you which direction the bullet was relative to you when it crossed your position, but not which direction it was traveling or where it originated from.
Using sub-sonic ammunition, reduces even this.