Patent ID: 6370254
Filing Date: 2002-04-09
Classification: G09F,H03G,H04N

Abstract:
A system for distributing audio-visual material over a plurality of locations in a building, the locations being spaced in different locations with any one location being acoustically affected by not only the immediate acoustic environment at that location but by the acoustic environment of at least one other of said locations, said system comprising:a source of audio material; a plurality of loudspeaker units each located at one of said locations and connected to said common source of audio material; a visual display unit associated with each loudspeaker; a video signal source for supplying video data complementary to said audio data to said display units; a plurality of automatic volume control circuits each associated with an individual loudspeaker and arranged to control the volume produced by said associated loudspeaker; a plurality of audio level sensing devices each connected to an individual one of said volume control circuits and located adjacent the speaker associated therewith, each volume control circuit producing a volume control signal arranged to increase or decrease the volume produced by the loudspeaker associated therewith in response to respective increases or decreases in ambient noise sensed by the sensing device associated therewith, the ambient noise being generated by the loudspeaker itself, by activity in the vicinity of the loudspeaker and by sound from at least one acoustically linked location, whereby the volume produced by each loudspeaker is responsive to ambient noise local to that loudspeaker; and means to cut out low frequency components of the ambient noise sensed by each of said sensing devices, wherein standing wave components having characteristics causing undesired gain fluctuations in said automatic volume control circuits are eliminated.