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1. (WO1979000046) SYSTEME D"ELIMINATION DE LA REVERBERATION ACOUSTIQUE
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS
1. A dereverberation system including two microphones connected to a signal processor
CHARACTERIZED BY:
first means (23, 24) for equalizing
the time delay between the signals from said two
microphones to develop two delay-requalized
signals;
second means (26) for equalizing the amplitudes of said two delay-equalized signals to develop two delay and amplitude-equalized signals; and
third means (27) for providing an output
signal responsive to said two delay and amplitude-equalized signals but only during selected time
intervals when said two signals are within a
preselected percentage amplitude tolerance of
each other.

2. The system of claim 1 further
characterized in that said first means (23, 24)
comprises:
fixed delay means (242) responsive to
the signal from one of said microphones;
variable delay means (232r235) responsive to the signal from the other of said microphones;
and
delay control means (25, 236) responsive
to the output signals of said fixed delay means
and said variable delay means for controlling the delay provided by said variable delay means.

3. The system of claim 2,
characterized in that
said fixed delay means (242) and said
variable delay means (232-235) are each preceded
by means (231, 241) for sampling applied signals.

4. The system of claim 3,
characterized in that said delay control means
(25, 236) maximizes a sum signal developed by
adding the output signals of said fixed delay means and said variable delay means.

5. The system of claim 1,
characterized in that said second means (26)
comprises:
a fixed gain stage (261) responsive to one of said two delay-requalized signals;
a variable gain stage (264) responsive to the other of said two delay-requalized signals; and
gain control means (267) responsive to the output signal of said fixed gain stage and the output signal of said variable gain stage
for controlling the gain of said variable gain stage.

6. The system of claim 1
characterized in that said third means (27) comprises a coincidence circuit.

7. The system of claim 1 characterized in that said third means (27) comprises:
fourth means (271, 272, 273) for
developing a difference signal corresponding
to the difference between said two delay and
amplitude-equalized signals of said second
means (26);
fifth means (274) for comparing the
difference signal to a prechosen threshold level which is a function of the signal levels of one or both of said delay and amplitude-equalized signals of said second means; and
sixth means (275) responsive to at least one of said two delay and amplitude-equalized signals of said second means for developing said output signal.

8. A system as in any one of the preceding claims further characterized by comprising:
a plurality of similar signal processors

(20-1, 2...N) to which said microphones are
connected, a filter (21, 22) interposed between each of said microphones and each of said processors for passing a preselected frequency band of the microphone signals, said frequency band being
different for each of said processors;
a filter (28) at the output of each of said processors for passing only those portions of the output signal of said third means which occupy the same frequency band passed to that processor, and
a summing network (30) responsive to the filtered output of each processor to provide the output of said system.