Maybe it's just me but did you ever notice that when a jet powered aircraft throttles down for approach, it sounds alot like an idling diesel like a CUMMINS !SM or DETROIT S60?
Just imagine the noise if aircraft had Jake brakes for landing. Oh wait, they do - they're called thrust reversers. Aren't they compression-release brakes (sort of)?
When JetBlue's Airbuses fly over here on their way into Long Beach they sometimes make a brief loud whine, almost like the compressor stage of their engines is varying its speed. I haven't heard that from Boeing 737s and 757s going into John Wayne airport here, so maybe it's peculiar to whatever engines are on those Airbuses?