They are a lot quieter than my .270 or 12 gauge
!
Some folks claim they are noisy, but I don't find mine to be. At 300 fps or so and shooting at a critter 30 yards away there is no time to 'duck' or 'jump' the shot. That's only a third of a second from release to target.
I've read that some people mod them to make them quieter, apparently it's fairly simple to do.
I haven't heard one of the new Matrix models fired so I don't know how much noise they put out.