Dereverberation system

DETAILED DESCRIPTION The principles of this invention may be employed by the use of a single processor or by the use of a plurality of processors.
When a single processor is employed, the entire signal band of the microphones is manipulated by that processor.
When a plurality of processors is employed, each processor manipulates a different band of the microphones' signal.
The single processor approach is, obviously, simpler and cheaper.
The multiprocessor approach perhaps yields an improved dereverberated signal.
For the purposes of this disclosure, the more general multiprocessor approach is described since the single processor system is a mere subset of the multiprocessor system described below.
In the block diagramatic illustration of the FIGURE, microphones 11 and 12, convert the echo-containing received sounds to electrial signals.
The signals received by the microphones come from a sound source and from reflection structures in reasonable proximity to the sound source.
Microphones 11 and 12 are spatially separated (an acceptable distance being 6 inches) and, therefore, both the direct and reflected sounds come to the microphones with different delays and with different magnitudes.
The basic approach of this invention for removing reverberation due to reflected signals employs the technique of separating the signals developed in microphones 11 and 12 into a plurality of frequency bands, independently manipulating the signals in each band, and combining the manipulated signals of the bands.
Within each band, the delay between the signals of the two microphones is equalized and the amplitudes of the delay-equalized microphone signals are also equalized.
The resultant signals do not differ much in the absence of uncorrelated signals at microphones 11 and 12 but differ significantly in the presence of uncorrelated signals.
The differences and similarities between the equalized signals of mirophones 11 and 12 are employed to advantage, in accordance with the principles of this invention, by comparing the signals to each other and by inhibiting the signals that are significantly dissimilar