ORTF stereo technique

The ORTF stereo microphone system, also known as Side-Other-Side, is a microphone technique used to record stereo sound. The ORTF stereo microphone system, also known as Side-Other-Side, is a microphone technique used to record stereo sound. It was devised around 1960 at the Office de Radiodiffusion Télévision Française(ORTF) at Radio France. ORTF combines both the volume difference provided as sound arrives on- and off-axis at two cardioid microphones spread to a 110° angle, as well as the timing difference as sound arrives at the two microphones spaced 17 cm apart.