Adaptive distance and near-field compensation applied to microphones

In voice acquisition, variations of the microphone distance introduce not only level changes, but also frequency response changes due to the near-field effect. This paper presents a method for adaptive distance and near-field compensation based on the talker-to-microphone distance and the microphone polar pattern. If available, the microphone orientation and the critical distance associated with the room acoustic can be taken into account to further improve compensation accuracy. Aimed at teleconference use, the significance of the critical distance for compensation is discussed for office and conference rooms. An example for the performance of the algorithm is provided, in which a sensor is applied to continuously measure a varying microphone distance.