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AssigneeJean-Claude Decaux
InventorsJacques Lewiner, Mathias Fink
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To protect a volume (2) arranged inside a room (3) in regard to outside noises E, use is made of an array of acoustic sensors (11.sub.j) receiving the noise E and arranged a distance A from the volume and of an array of acoustic sources (15.sub.k) arranged a distance B less than A from the volume and signals S are applied to these sources, these signals being summations of the double convolution products of the function E.sub.j (t) with two functions f.sub.ij (t) and g.sub.ik (-t) which are directly deducible from the impulse responses gathered, on the one hand, at the sensors (11.sub.j) from pulses emitted by the sources (10.sub.i) carried by a fictitious barrier (6) delimiting the volume and, on the other hand, at sensors (12.sub.i) stationed at the same places as these latter sources (10.sub.i), from pulses emitted by the above sources (15.sub.k).
A device for protecting from outside noises a given volume arranged inside a room, said device comprising an array of acoustic sensors receiving noises to be canceled, an array of acoustic sources, said arrays being arranged at two distinct distances, A and B, respectively, from said volume, the distance B being less than the distance A, and an electronic circuit, at least partly interposed between said sensors and the said sources, for calculating, in time periods less than (A-B)/v, whereas v is the speed of sound in air, for each noise received by a sensor, a plurality of signals which are applied instantaneously, respectively, to the sources, so as to provide canceling of said noise in said volume, said electronic circuit comprising means for determining impulse response laws of the room corresponding to emissions of short acoustic pulses, for storing said response laws, for determining counter signals deduced from said response laws by time inversion, for storing said counter signals, and for forming convolution products of some of said response laws, some of said counter signals and some of the signals received by the sensors.
A process for protecting from outside noises a given volume arranged inside a room, said volume being defined by a reticulate array of points i, arranged in the volume, by using a device comprising an array of acoustic sensors receiving noises E.sub.j (t) to be canceled, an array of acoustic sources, said arrays being arranged at two distinct distances, A and B, respectively, from said volume, the distance B being less than the distance A, and an electronic circuit, at least partly interposed between said sensors and the said sources, for calculating, in time periods less than (A-B)/v, whereas v is the speed of sound in air, for each noise E.sub.j (t) received by a sensor, a plurality of signals S.sub.k (t) which are applied instantaneously, respectively, to the sources, so as to provide canceling of said noise in said volume, said electronic circuit comprising means for determining impulse response laws of the room corresponding to emissions of short acoustic pulses, for storing said response laws, for determining counter signals deduced from said response laws by time inversion, for storing said counter signals, and for forming convolution products of some of said response laws, some of said counter signals and some of the signals received by the sensors, the process comprising providing that each of the signals S.sub.k (t) which are applied to the sources from the electronic circuit is equal to:
Dependencies are inferred from the claim text.