Business part of the ear?
Yes, precisely that. The part of the ear which carries out its "
business" which is the sense of hearing. In your brief listing this is the Cochlea. Your listing appears not to include the semi-circular canal system, which, of course, is also of absolutely fundamental importance in aviation.
If blood turbulence flowing through arteries could be heard it is likely the turbulent flow would be in all arteries near both the ears and if it was possible to hear that turbulence it would be heard in both ears not just one
Simply not true, I'm afraid. Firstly, the sound of turbulent flow is not transmitted very far. But, more importantly, atherosclerotic deposits are not likely to be laid down regularly and smoothly in arterial walls. There can be areas where there is significant narrowing over only a very short distance (just as in coronary arteries). The turbulence (and therefore the sound) will be only where the flow is restricted.