These are uni-directional microphones mounted on booms which can be swung overhead and aimed at individual speakers; they are mainly used for recording drama, and require skilled operation by an assistant.
Invented by Robert Showen, an electronics engineer, the system consists of eight omnidirectional microphones mounted on rooftops and utility poles.
In the late 1960s, Aiwa and Sony offered headphones with a pair of microphones mounted on the headband.
The ceramic microphone, mounted in the crook was developed to withstand high sound pressure and moisture levels.
One system, known as Boomerang, uses a bundle of seven microphones, each facing a different direction, mounted on top of an 18-inch pole.
Sound from the pointer travels to four overhead microphones mounted in a rigid frame.
It had four microphones mounted in front of fiberglass parabolic reflectors (reminiscent of a flower) on top of a spine-like column of aluminium castings.
It has a small microphone, mounted on the rearview mirror, that can be wired through the stereo speakers and is intended to pick up even soft voices.
Sigur Ros used instruments made for the occasion, including one with microphones mounted in dancers' pointe shoes.