With a suppressor the expanding gases are redirected in and around many baffles into expansion chambers. Then you don't have high speed gases expanding out of the muzzle. That decreases the sound signature, usually from 25-30 db. The recoil is decreased by the amount that is normally attributed to the expanding gases. That energy is turned into heat. If you put some water into a suppressor (described as a "wet" suppressor, go figure), the efficiency in decreasing the sound is increased. The heat is absorbed by the water, which is converted into water vapor.
JCN

When I was a Co Cdr my 1st SGT came had just come from Delta Force (most impressive leader I have ever met, BTW). Anyway, he told me that suppressors became louder with every shot, and that was an issue, so it sounds like they have made progress there.

He also said the same as you JCN with respect to pipointing the crack of a bullet. Very difficult; seems to come from 90 deg away from where it is.

skl1,
The AMA is a political organization, but not an effective one. They want docs to ask people about the # of guns in the house under the guise of "child safety". Since it is safer to have guns in the house than to not have any, I think you are right about encouraging the use of suppressors to safeguard America's ears.

Some of the newer suppressors are amazing. The first baffle is made of Inconel and the rest is a very high quality stainless steel. You can run a full belt through a machine gun with one on. It will start glowing red after a while, but it keeps working. They are a godsend for our troops. You can shoot, move and communicate, even indoors. I believe eventually whole units (not just spec ops types) of troops will be issued suppressors to use on their M-4's, especially if they are likely to be fighting in an urban scenario.

One interesting thing. Even though you can hear the supersonic "crack" of the bullet, you can't localize the source direction. There is an auditory illusion that the bullet is coming from the direction that the bullet is actually going to (you don't hear the sonic "crack" of the bullet until it is past you).

Finally, you get more "bang" for your buck if you use a suppressor on a small bore, high intesity cartridge. Suppressors and .223's go together like Bill Clinton and lying. With a 458 Lott, on the other hand, you are basically wasting your money.

JCN