I often wondered about a possibly connected thing about airplane pilot's microphones:

Why is it that pilots, when addressing the fliers over intercom always have terrible sound quality? You'd think that airlines could afford a high-quality microphone considering the cost of the plane and the pilot's time. Air traffic control should appreciate quality audio as well.

There could be some ruggedness requirement to these microphones that takes precedence over audio quality. Maybe they must withstand decompression?