A-B Stereo

Sometimes known as “time difference stereo,” A-B stereo is a stereo miking technique that employs two spaced omnidirectional microphones to capture a stereo image. The microphone spacing introduces small differences in the time or phase information contained in the audio signals (according to the relative directions of the sound sources). As the human ear can sense these time and phase differences in audio signals and use them for localization, they will act as stereo cues to enable the listener to “capture the space” in the recording and experience a stereo image of the soundfield. Omnidirectional microphones and A-B stereo are often the preferred choice when the distance between the microphone and the sound source is large. One reason is that true omnidirectional microphones are able to capture the true low frequencies of a sound source regardless of the distance, while directional microphones are influenced by the proximity effect. Directional microphones will, therefore, exhibit loss of low frequencies at larger distances. (See spaced omni.)