Q400 = actuators fitted to fuselage frames alter the cabin internal diameter by thousands of an inch to counteract pressue pulses created by both sixbladed prop tips rotating at 850,900 or 1020 rpm. Pickup is electronic and acoustic. Reduces by a few db. Very noticeable when an actuator goes out of sync.
No anti noise through speakers.
Prop rpm can be electronically maintained at 850 on approach for earth dwellers comfort too.
Best solution for noise is to fly on the high bypass version of the Q4 = C series.
Last edited by darkbarly; 26th Sep 2016 at 06:29.
Reason: Typo