[DrHenley]

There are four different sounds that can be made by a gunshot.

1) "BOOM" - that's the sound the "projectile exhaust" makes. It's instantaneous, not an extended sound.

2) For supersonic rounds there is a "CHEOWWWW" made by the bullet breaking the sound barrier and continues as long as the bullet is supersonic and in the air. It is not a whining sound.
You can usually tell whether a gunshot came from a duck hunter or a deer hunter because the duck hunter's shotgun goes "BOOM" and the deer hunter's rifle goes "BOOM cheOWWWW". This may be what you are thinking of. Subsonic handguns like 45 Colts only go "BOOM."
Suppressors can dampen the "BOOM" but not the "cheOWWWW" because that sound is generated after the bullet leaves the muzzle.

3) If there are objects for the sound to bounce off of, there is an echo which may be extended and often reverberates (lasts longer than #2) The exact sound of the echo depends on how many objects and how far they are. Much of the echo from a rifle shot is actually from the "cheOWWWW" not the "BOOM" and can reverberate for several seconds in the right conditions.

4) If the bullet ricochets then you get an whine from the deformed bullet. This is the only kind of actual "whine" a gunshot can make.

Movie and TV gunshot sound effects are mostly unrealistic, so you cannot base anything off of what you hear in movie or TV.
IT'S JUST MAKE BELIEVE!

If you will tell me what show you were watching and which episode and time, I'll try to find it and listen to the sound.