(acoustic-pick-up, omnidirectional, hyper-cardoid) 1) Device which, when attached to an acoustic musical instrument, converts sound vibrations into an electrical signal. 2) A way of describing the directional sensitivity of a microphone. An Omnidirectional microphone has equal pick-up from all around, a Cardoid microphone is more sensitive from the front, a Hypercardoid has very strong directionality from the front. A figure-of eight microphone picks up front and rear, but rejects sound from the sides.