Process and apparatus for speech privacy improvement through incoherent masking noise sound generation in open-plan office spaces and the like

• US 4,059,726 A
• Filed: 06/18/1976
• Issued: 11/22/1977
• Est. Priority Date: 11/29/1974
• Status: Expired due to Term

• Current Assignee: Bolt Beranek and Newman, Inc.
• Original Assignee: Bolt Beranek and Newman, Inc.
• Inventors: Horrall, Thomas R., Watters, Bill G., Nacey, Michael
• Primary Examiner(s): Cooper, William C.
• Assistant Examiner(s): Kemeny, E. S.
• Application Number:
  US05/697,562
• Time in Patent Office: 522 Days
• Field of Search: 179/1 AA, 179/1 AT, 179/1.5 R, 179/1.5 M, 179/2.5 R
• US Class Current: 381/73.1
• CPC Class Codes: H04K 1/02 by adding a second signal to make the desired signal unintelligible

Abstract

The invention involves the use of a plurality of incoherent noise generators distributed, in one embodiment, along ceilings in open-plan and partitioned office spaces and the like, to diffuse masking sound energy through acoustical tile and other false ceiling structures while tailoring the same for speech privacy results, by providing a uniform, delocalized and incoherent masking sound space.

Claims

1. A process of distributing masking sound in an open-plan space and the like, that comprises, independently and incoherently generating and radiating noise at a plurality of positions laterally separated from one another above a sound-transmitting surface covering such an open space;

shaping the frequency spectrum of the noise to correspond substantially to that desired for speech privacy masking; and

adjusting the lateral separation of noise radiation positions from one another to control the diffusion and distribution of the masking noise sound cumulatively transmitted through and below said surface into the open space, in order to provide a uniform, de-localized incoherent masking radiation within said open space.

2. A process as claimed in claim 1 and in which intelligence signal radiation is superimposed upon said incoherent masking noise radiation.

12. A process as claimed in claim 1 in which said positions are laterally separated from one another in two dimensions and are two-dimensionally distributed over substantially the entire area of a sound-diffusing surface covering an open-plan space having an insignificantly small reverberant field, in which the noise generated at each position is free of cyclic correspondence to the noise generated at any other position and in which the noise generated at any instant at any position is unrelated to the noise then generated at the other positions.

3. Apparatus for distributing masking noise through a false ceiling surface and the like into an open space therebelow, having, in combination, a plurality of independent incoherent noise-generating units, each provided with a separate electronic noise source, frequencing shaping filter, amplifying and sound radiating means;

means for mounting said units at a plurality of positions laterally spaced over the ceiling surface;

means for powering said units from ceiling power conduit means; and

means for tuning the shaping filter and for adjusting the height of said units above said ceiling surface and adjusting the lateral separation of said units to provide a predetermined speech privacy noise attenuation spectrum below said ceiling surface, said surface being selected to diffuse the noise radiated from the plurality of units to provide cumulative de-localized incoherent masking radiation within said open space.

4. Apparatus as claimed in claim 3 and in which said tuning and adjusting means are adjusted to provide substantially the following relative levels, measured in octave bands:

125 Hz-0db;

250 Hz-3db;

500 Hz-6db;

1000 Hz-11db;

2000 Hz-18db;

4000 Hz-26db;

8000 Hz-36db.

5. Apparatus as claimed in claim 3 and in which means is provided for receiving and demodulating radio-frequency carried intelligence signals and adding the same to the incoherent masking noise from said electronic noise source to radiate with the noise from said sound radiating means.

6. Apparatus as claimed in claim 5 and in which means is provided for carrying said intelligence signals along said power conduit means, and said receiving and demodulating means is coupled to said power conduit means.

11. Apparatus as claimed in claim 3 and in which diffusing and frequency-spreading means is provided below said units.

13. Apparatus as claimed in claim 3 in which said positions are laterally separated from one another in two dimensions and are two-dimensionally distributed over substantially the entire area of a sound-diffusing ceiling surface, in which said noise-generating units generate noise at each position free of cyclic correspondence to the noise generated at any other position, and in which the noise generated at any instant at any position is unrelated to the noise then generated at the other positions, in order to provide a uniform, delocalized incoherent masking radiation throughout said space.

7. Apparatus for distributing masking noise into an open space, having, in combination, a plurality of independent incoherent noise-generating units, each provided with a separate electronic noise source, frequencing shaping filter, amplifying and sound radiating means;

means for mounting said units at a plurality of positions laterally spaced from one another;

means for powering said units from power conduit means associated with said space; and

means for tuning the shaping filter and for adjusting the height and the lateral separation of said units to provide a predetermined speech privacy noise attenuation spectrum within said space, and to provide incoherent masking radiation there within.

8. Apparatus as claimed in claim 7 and in which said tuning and adjusting means are adjusted to provide substantially the following relative levels, measured in octave bands:

125 Hz-0db;

250 Hz-3db;

500 Hz-6db;

1000 Hz-11db;

2000 Hz-18db;

4000 Hz-26db;

8000 Hz-36db.

9. Apparatus as claimed in claim 7 and in which means is provided for receiving and demodulating radio-frequency carried intelligence signals and adding the same to the incoherent masking noise from said electronic noise source to radiate with the noise from said sound radiating means.

10. Apparatus as claimed in claim 9 and in which means is provided for carrying said intelligence signals along said power conduit means, and said receiving and demodulating means is coupled to said power conduit means.

14. Apparatus as claimed in claim 7 in which said positions are laterally separated from one another in two dimensions and are two-dimensionally distributed over substantially the entire area of a sound-diffusing ceiling covering said open space, in which each of said noise-generating units generates noise free of any cyclic correspondence to the noise generated by any other noise generating unit, and in which the noise generated at any instant by any unit is unrelated to the noise then generated by the other units, in order to provide a uniform, delocalized incoherent masking radiation throughout said space.