In any attempt at creating natural audio-visual communication between two remote locations, acoustic echoes are generated due to the coupling between the loudspeakers and microphones in each conference room. If ignored, these echoes can completely disrupt audio communication. Teleconferencing systems today use single-channel (monophonic) speech communication. In order to recreate a natural ‘‘presence’’ in the remote location, multichannel (stereo) communication is desirable, and will no doubt be the preferred future mode of teleconferencing between two spatially separated groups of participants. A third type of conference is a desktop conference between several locations. In such applications the remote participants are displayed on a screen, and synthesized stereo may be used to simulate sound coming from the direction of each of them. The talk will discuss the characteristics of echoes in all such situations, and the solutions currently available to deal with them. The solutions can also be useful for eliminating disturbances other than echoes, e.g., the sound from a car’s stereo system picked up by the transmitter of a hands-free telephone.