They’re Suppressors, not “silencers”.
They reduce the overall sound signature, but do not “silence” anything.
If using subsonic ammo, it’s quieter, but there’s still sound.
Hiram Maxim called them silencers when he invented and sold them. You can buy one at silencershop.com.
https://en.wikipedia.org/wiki/Silencer_(firearms)
https://www.silencershop.com/silencers.html