Abstract: An acoustical enclosure for isolating high-frequency noise produced by automatic business machines, such as typewriters and teletypes. A top paper-feed housing is removable and a midsection is hinged to permit access to the enclosed machine. An exhaust fan removes heated air from the enclosure and an air-intake lip at the front of the enclosure permits ambient-temperature air to be taken into the enclosure.

Abstract: An acoustical wall panel has a core of a plurality of layers of glass fiber pressed together and having a density ranging from approximately two pounds per cubic foot at the front surface to approximately six pounds per cubic foot at the rear surface. A plurality of cavities are formed on the front surface of the core. The front of the panel is covered with fabric, and the rear is covered with a septum to provide a barrier to the transmission of sound pressure waves. The cross-sectional area, depth and spacing of the cavities are selected to improve absorption of sound in the intelligence range of speech while having less absorption in the lower frequency range to permit a desirable background or ambient noise to exist. The spacing and shape of the cavities also provides a smooth, continuously changing curvature in the cavity side walls to increase the surface area and enhance the capacity of the panel to absorb sound at flanking angles of incidence.

Abstract: A self-contained sound masking package including a housing having an interior forming a loudspeaker enclosure in the bottom of which is disposed an electric circuit arranged to be connected to an associated source of electrical power for producing a voltage having a predetermined frequency range within the audible spectrum and with the frequencies at predetermined relative decibel levels, the voltage being applied to a transducer such as a loudspeaker having a coil supported in the housing interior adjacent the top of the housing for introducing an audible sound of the predetermined frequency range and decibel levels into the area surrounding the housing, together with means for connecting a remote signal source to the circuit to provide a supplementary audible output from the loudspeaker into the area and the electric circuit being preferably in the form of a printed circuit board and having filter means which may be selectively activated to provide an audible output from the loudspeaker throughout at least