Patent US 4,087,633

Disclosed is a signal dereverberation system employing two spatially separated microphones. The microphones' signals are processed by first equalizing the delay in the signals applied to the microphones, and following the delay equalization, the signal magnitude of the two microphones is equalized and compared at short intervals in a coincidence circuit. Signals that are within a predetermined percentage tolerance of each other are utilized, while signals outside the predetermined tolerance are inhibited. The output signal of the coincidence circuit is filtered to remove out-of-band signals introduced by the switching within the coincidence circuit. Processing of the microphones' signals can be performed in a single processor, covering the entire signal band; or in a plurality of processors, each independently processing a different band of the signal. When a plurality of processors is employed, the output signals of the plurality of coincidence circuit (one in each processor) are appropriately filtered and combined to form the desired nonreverberant signal.