ORTF stereo technique

It was devised around 1960 at the now-defunct Office de Radiodiffusion Télévision Française (ORTF).

[1] The microphones should be as similar as possible, preferably a frequency-matched pair of an identical type and model.

Since the cardioid polar pattern rejects off-axis sound, less of the ambient room characteristics are picked up.

As with all microphone arrangements, the spacing and angle can be manually adjusted slightly by ear for the best sound, which may vary depending on room acoustics, source characteristics, and other factors.

This arrangement is defined as it is because it was the outcome of considerable research and experimentation, and its results are predictable and repeatable.