Why? In real life, even guns with supressers make a bang, just not as loud because all a supresser is doing is getting rid of one bang, guns make two noises, 1. The explosion in the chamber and 2. the bullet leaving the barrel and breaking the sound barrier. Supressed weapons get rid of #1, you'd need sub-sonic ammo for #2. So it'd still make a bang just not as loud.
Suppressed weapons do not entirely get rid of the explosion in the chamber. It suppresses the noise to about 130-140dB the quietest you can get is about 117dB which can still be heard, an ambulance sirens is around 100dB same with small firecrackers, a person speaking at normal volume is around 50dB. So in comparison suppressed firearms can be kind of loud.
But most of the noise generated is gas escaping the muzzle and the firearm's action when ejecting a round and reloading a new round, the round escaping, traveling to it's target and when a round impacts. Suppressors are "hearing safe" which means you can fire a suppressed weapon without the need for ear protection.