Totally hypothetical question:
A wealthy man approaches asks you to design the optimal microphone solution for an in-car hands-free calling system.
He has three goals: A: eliminate background noise B: eliminate feedback C: optimize voice quality
He has only three constraints: A: the solution must use fewer than two microphones B: it must plug into the 'mic-in' on the hands-free system using a 3.5 MM male connector C: you can not adjust the audio-out C: the solution must not be visually intrusive (he welcomes your interpretation of 'intrusive')
The wealthy man provides you with all the money, time, expertise, and equipment you require?
What would you build?