INA-3 or Ideal Cardioid Arrangement (ICA)

This microphone technique was developed by Günther Theile. INA is an acronym for Ideale Nieren Anordnung, German for “ideal cardioid arrangement,” and it is sometimes called by that name. The INA-3 is a technique for the three-microphone front array, and most commonly is used with the rear array in the INA-5. The INA-3 uses a cardioid microphone for the center channel placed 17.5 cm (7 in) in front of two cardioids used for left and right channels, pointing outwards. The spacing between the left and right microphones is 35 cm (14 in). Distances between the front three microphones can be changed to adjust the ambient response.