Gun silencer (Suppressor)

How sound from fired bullet will be suppressed by silencer?🤔🤔

Function of gun: 

To know the working of silencer (most commonly called as suppressor), it's better to first understand what happens inside a gun when we fire a bullet. when bullet is fired, gun powder at the back of the bullet gets ignited and pushes the bullet forward same as in case of rocket launching. The pressure generated will be so high  to enable to give sufficient Initial velocity to bullet. After bullet passes out from the gun, propellant gas inside the gun will be exposed to atmosphere, creating a disturbance in surrounding air in the form of sound waves.

Suppressor:

So to decrease sound,  propellant gases must be allowed to expand in a better manner. That's what exactly a suppressor does. Suppressor contains chambers to expand the propellant gases gradually, where the propellant gas is slow down and gets cooled and hence pressure inside the suppressor will drops down and even after exposed to atmosphere disturbance created is negligible. Generally suppressor's reduces the intensity of sound from 140 dB to 20 dB (approximately).

But the sound generated from the flight of bullet can't be suppressed by suppressor

NOTE: CONTENT IS LIMITED TO MY KNOWLEDGE AND COMMENTS ARE MOST WELCOME