Hi guys, its been awhile since i have been back. Right now, i am involved in some research on aeroacoustics and i have been trying to get some of the basic fundamentals on aerodynamic generation of sounds. Unfortunately most of the online literature do not give much details on the physics of such mechanism. I hope you guys could provide me with some guidance. From my understanding, sounds are perceived by us through changes in air pressure that is picked up by our ears. And most of the time, such changes in air pressure (compressions and rarefractions) are generated by objects vibrating in a medium and the compression waves generated propagates outwards and reaches us. However, in aeroacoustics, which is sound generated aerodynamically, there do not seem to be a vibrating source here (i think..). Sound is generated by turbulent shear flow instead. What I understand is that when air flows across a surface, and becomes turbulent, vortex shedding occurs and noise is generated. But in this case, how is the noise picked up by our ears if there are no changes in pressure? Could it be that due to vortex shedding, the source vibrates and hence produces sounds? Or are the vortices the one that generate compression hence sounds here? How is this applicable to aircraft noise generated when air flows over edges of flaps and slats when separation occurs? Thank you all so much for you help!