“…A good example of this decision is presented in [37] where, assuming there are only two sound sources in a meeting room, the beamforming technique 'decides' which sound source is assigned to which sound source class. These decisions are carried out at specific intervals, with which several methodologies can be employed for tracking purposes, such as Kalman filters [18] or particle filtering [38]. Another technique that is somewhat related to this type of approach, discussed and refined in [39], is known as the position-pitch (PoPi) plane, where, instead of mapping energy values onto the directional plane, a pitch spectrum is estimated per direction, providing possibilities to jointly estimate the DOA and pitch of sound sources, which, in turn, provides additional information to locate more than one source in the same direction.…”