Auto-adjusting sound masking system and method

• US 20060009969A1
• Filed: 06/22/2004
• Published: 01/12/2006
• Est. Priority Date: 06/21/2004
• Status: Active Grant

• Current Assignee: Soft DB Incorporated
• Original Assignee: Soft DB Incorporated
• Inventors: Boudreau, Alex, L'Esperance, Andre
• Granted Patent: US 7,460,675 B2
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10K 11/1752 Masking
• CPC Class Codes: H04K 2203/12 for acoustic communication
• CPC Class Codes: H04K 3/42 characterized by the control of the jamming frequency or wavelength
• CPC Class Codes: H04K 3/45 characterized by including monitoring of the target or target signal, e.g. in reactive jammers or follower jammers for example by means of an alternation of jamming phases and monitoring phases, called "look-through mode"
• CPC Class Codes: H04K 3/825 by jamming
• CPC Class Codes: H04K 3/94 related to allowing or preventing testing or assessing

Abstract

A system and method for generating a masking noise level and spectrum automatically adjusted to obtain a target masking noise spectrum in a room. The system comprises a white noise generator and a mask filter automatically determined according to a correction of an acoustical response of the room and to the target masking noise corrected by an ambient noise.

Claims

1. A sound masking system emitting a target masking noise in a room, comprising a white noise generator and a mask filter, wherein said mask filter is automatically determined according to a correction of an acoustical response of the room, obtained when loudspeakers emit a white noise generated by said white noise generator, and to the target masking noise corrected by an ambient noise obtained when the loudspeakers are off, said mask filter once determined filtrating a white noise generated by the white noise generator to yield the target masking noise emitted in the room.

2. The sound masking system according to claim 1, further comprising an acquisition unit, said system being connected to microphones sending signals to said acquisition unit when the loudspeakers emit the white noise generated by said white noise generator to measure the acoustical response of the room;

and said microphones sending signals to said acquisition unit, when the loudspeakers are off, to measure the ambient noise.

3. The sound masking system according to claim 1, wherein the acoustical response of the room comprises a contribution due to the loudspeakers whatever a location of the loudspeakers in the room, and the ambient noise includes an acoustical coupling with neighboring zones of the room.

4. The sound masking system according to claim 1, said system being embedded in a digital sound field processor board (DSP).

5. The sound masking system according to claim 1, said system being connected to a drive unit.

6. A method for generating a target masking noise in a room, comprising:

providing a white noise generator;

selecting a target masking noise;

determining a mask filter according to the selected target masking noise; and

filtering a white noise generated by the white noise generator through the mask filter;

whereby said step of determining a mask filter comprises obtaining an acoustical response and an ambient noise of the room and determining a target noise correction filter.

7. The method according to claim 6, wherein said obtaining the ambient noise comprises obtaining an acoustical coupling with neighboring zones of the room.

8. The method according to claim 6, wherein said obtaining an acoustical response of the room comprises locating loudspeakers at a final location thereof in the room;

emitting a white noise, generated by the white noise generator, by the loudspeakers; and

measuring a resulting noise in the room by microphones; and

said obtaining the ambient noise comprises measuring a noise in the room by microphones without emission of the loudspeakers.

9. The method according to claim 8, wherein said obtaining the acoustical response of the room comprises obtaining a contribution due to the loudspeakers whatever a location of the loudspeakers in the room.

10. The method according to claim 6, wherein said step of determining a noise correction filter comprises:

subtracting the ambient noise frequency by frequency from the target masking noise to yield a corrected masking spectrum; and

convoluting, in a time domain, the corrected masking spectrum with a spectrum of the acoustical response of the room.

11. The method according to claim 6, further comprising testing the mask filter by measuring a masking noise emitted in the room through the mask filter, and by comparing the measured masking noise emitted in the room with the target masking noise.