It's the lock time that makes them quieter hosts. Hammer fired guns have more resistance unlocking, and also less resistance returning to battery (no striker to reset). That means lower port noise, and greater reliability returning to battery with the extra mass of the reciprocating assembly. Lots of striker fired guns struggle with the latter, especially running heavier (>10 ounce) cans.
The mechanical noises of either action type are below the SPL of the shot with a centerfire pistol. You might hear them, but they will not be the loudest thing.
This is not speculative. I manufacture & repair silencers for a living using 3, 4 and 5 axis CNC machines as well as manuals, I own precision impulse sound metering equipment, and have a 100 yard range behind the shop where we test. 1911s, 3rd gen smiths, Beretta 92, CZ-75 (and copies), etc. are quieter at ear than Glocks, M&Ps, XDs, RPs and the like.