Adaptive Stereo Acoustic Echo Cancelation in reverberant environments

Acoustic Echo cancelation (AEC) is an important tool which is needed to reduce the echo levels heard by the speaker in communication systems such as full-duplex hands free teleconferencing system. This echo is the result from the loudspeaker to microphone coupling in the near-end room. Adaptive filtering techniques are usually used in order to estimate the near-end room loudspeaker to microphone impulse response. The estimated echo signal is subtracted from the received microphone signal, thus reducing the level of the returning echo to the far-end room. Stereophonic communication systems provide a more lifelike conversation quality since the participants can use the added spatial information to distinguish the current speaker location. This work discusses a stereophonic system which consists of two microphones in the far-end room connected to two loudspeakers in the near-end room, and one microphone in the near-end room connected to a single loudspeaker in the far-end room. The analysis for a second set of a near-end room microphone connected to a far-end room loudspeaker is easily deducted due to the problem symmetry. In the discussed stereophonic system, a single speaker signal in the far-end room is received by the far-end room microphones and transmitted to the near-end room loudspeakers. The two loudspeakers signals are then received by the near-end room microphone and transmitted back to the far-end room loudspeaker, thus producing the stereophonic echo. The current available solutions that reduce the stereophonic echo focus mainly on solving problems caused by the high correlation between the two far-end room microphone signals (the near-end room loudspeakers signals). This high correlation is caused by the single origin of the two signals (the far-end room speaker). Therefore the