Sound masking system for open plan office

• US 3,985,957 A
• Filed: 10/28/1975
• Issued: 10/12/1976
• Est. Priority Date: 10/28/1975
• Status: Expired due to Term

• Current Assignee: Dukane Corporation
• Original Assignee: Dukane Corporation
• Inventors: Torn, William R.
• Primary Examiner(s): Birmiel, Howard A.
• Application Number:
  US05/626,240
• Time in Patent Office: 350 Days
• Field of Search: 179/1.5 M, 179/1.5 R, 179/1 GA, 179/1 E, 181/198, 181/154, 340/15
• US Class Current: 381/73.1
• CPC Class Codes: G10K 11/1754 Speech masking
• CPC Class Codes: H04K 2203/12 for acoustic communication
• CPC Class Codes: H04K 2203/36 including means for exchanging jamming data between transmitter and receiver, e.g. in forward or backward direction
• CPC Class Codes: H04K 3/68 using passive jamming, e.g. by shielding or reflection shielding of apparatus or components against electric or magnetic field H05K9/00
• CPC Class Codes: H04K 3/825 by jamming

Abstract

This invention relates to a system for masking conversation in an open plan office. A conventional generator of electrical random noise currents feeds its output through adjustable electric filter means to speaker clusters in a plenum above the office space. Each cluster has two speakers in a trigonal prism-shaped cabinet, symmetrically disposed about an axis of symmetry, oriented to be vertical. The speaker arrangement is such that, throughout the open plan office area, including below speaker clusters, the background sound energy level horizontally in the open plan office space has a generally constant value except for a modification which provides for a quiet region below a cluster. By proper spacing of clusters horizontally along the plenum region, transmission of background masking sound through an acoustic ceiling throughout an open plan office space, conversation in one region of the office cannot be distinguished at a distance of the order of about 15 feet or more.

Claims

1. An acoustic masking system for obtaining conversational privacy in an open plan office space having a floor and an acoustic ceiling wiith a plenum space above said ceiling, said plenum space having its own sound reflecting ceiling, said office acoustic ceiling having characteristics incuding sound absorption, reflection and transmission therethrough, said system having a generator for providing electric currents which are reproduced by a loud speaker as predetermined random noise, and speaker means connected to be energized by said generator output, said speaker means consisting of at least one cluster of two speakers for mounting in said plenum region, a cluster having a trigonal prism-shaped speaker cabinet having three flat prism panels shaped and assembled to form a triangular prism-shaped hollow cabinet with two triangular end plates, a loud speaker mounted in two of said prism side panels, each panel functioning as a baffle board for propagating sound outwardly by its speaker, said cabinet being adapted to be installed in the plenum region to orient said prism horizontally, said speakers being symmetrically disposed in their panels when said cluster is installed and being equally inclined from a horizontal plane in such installed position, said speakers being similar and adapted to be simlarly energized so that sound waves from said speakers can travel along air paths to solid surfaces for reflection therefrom, absorption thereby, and transmission therethrough to provide masking background noise in the open plan office.

2. The system according to claim 1, wherein said speakers are of the 8 inch permanent magnet dynamic type.

3. The system according to claim 1, wherein filter means are connected between the generator and speaker means.