Aaaah, the ATR Catflap - very useful, unless you flew (as I did) for a company which had Tech Logs too big to pass through the hole!
The F28 Mk100 - or Fokker 100 - had the air conditioning packs under the flight deck floor, as the thrust reversers were a late modification to the aircraft, and some weight had to be moved forwards to compensate. The engines were almost silent from the flight deck, but as the packs shut down on TO/GA selection, it's the only aircraft I know which got noticeably quieter when you started the takeoff!
That said, we were very aware of passenger comfort in the rear-most rows, and used to climb in manual thrust and V/S very often to keep the noise changes to a minimum. How many Chief Pilots now would be horrified to learn that!