Abstract: Noisemasking speakers are positioned in an array to direct noise into a space which is to be used by a number of people so that individual privacy is assured. The array is divided into four or more sets of speakers. The single noise source is equalized, and the same equalized noise is fed to the four speaker sets through time-delay devices so that the noise from each set has low correlation with each of the other sets.

Abstract: Background sound system provides audiofrequency energy in a large office space for masking speech. The system includes a plurality of downwardly directed speakers in speaker enclosures mounted on the top of the suspended ceiling defining the office space. The speakers are thus directly acoustically coupled with the office space.

Abstract: Masking-noise speakers are positioned in an array of lines and rows to direct masking noise into a space. Two separate noise generators provide noise signals respectively to two equalizer-amplifiers which provide their signals respectively to first and second narrow band equalizers. These channel signals are respectively delivered through power amplifiers to first and second sets of speakers in the speaker array. The first and second channel signals are combined to produce a third channel signal, are power amplified, and delivered to a third set of speakers in the array so that no two adjacent speakers on any line or row are powered by the same noise signal. In a modified arrangement, the combination of the first and second channel signals is made after power amplification.