Definitions for "Bidirectional microphone"
A microphone that picks up sound equally from two directions. A good example of this type of microphone would be if you were able to put two cardioid microphones back-to-back. The resulting microphone would pick up sound from two directions and reject sound from the sides. It’s common to see such a microphone used for recording or braodcast applications. Typical specifications are: coverage angle=90-degrees (each side), maximum rejection=90-degrees (2-points) see also: cardioid; hypercardioid; omnidirectional; supercardioid; polar pattern
( figure-eight microphone) A mic sensitive to sounds arriving from on-axis (front) and... ( more)
A microphone that picks up equally from two opposite directions. The angle of best rejection is 90 degrees from the front (or rear) of the microphone, that is, directly at the sides.