S-3 engine 'hoover' was both an increasing, or decreasing, noise depending upon power setting and amount of power increase or decrease and the rate of change.
Another interesting aerodynamic event is to listen to wingtip vortices. Different a/c have distinctly different vortices noises. Learned that playing golf at the golf course just south of KSEA. Got to the point that we'd try to guess the a/c type by the vortice noise in the trees.