Abstract: A method of absorbing sound generated within a clean-room environment and the sound-absorbing panel for carrying out that method, wherein said sound absorbing panel comprises a fibrous core material enclosed in a non-porous membrane, said membrane being attached to at least one of the extensive surfaces of said fiberglass core in a series of closed geometric figures. The membrane occupying the central portion of each of said geometric figures defines a diaphragm, the dimensions of the diaphragm being configured such that the lower order natural frequencies of vibration of each of the independent diaphragms correspond substantially to the frequency range of sound to be absorbed.

Abstract: An electric motor includes a motor frame and a fan driven by the motor disposed adjacent one end of and inside the motor frame. The fan draws air in through an inlet opening formed in the motor frame at the end of the frame opposite the fan. The air flows over and cools internal components of the motor and is exhausted by the fan in a radially outward direction through an outlet opening in the motor frame. A silencer for the motor includes an acoustical panel which at least partially surrounds the motor frame, is spaced from the frame, and is disposed to intercept air flowing radially from the outlet opening in the frame. The acoustical panel extends from the fan end of the motor frame partway along the length of the frame so as to direct air exhausted from the fan along the frame between the frame and the panel. The panel includes a layer of air-permeable sound absorbing material and air-impermeable sheet disposed adjacent to the sound absorbing material on the side of the material opposite the motor frame.

Abstract: An electric motor has a motor housing and a fan at one end of the housing driven by the motor. The motor also has structure for directing air exhausted from the fan along the length of the motor housing to cool the motor. A silencer for the motor comprises an acoustical end panel disposed transversely of the motor housing and spaced axially from the end of the housing where the fan is mounted. A second acoustical panel is configured to define an open-ended member that at least partially surrounds the motor housing and is spaced from the housing. Each panel includes a layer of air-permeable sound absorbing material and an air-impermeable sheet disposed adjacent to the sound absorbing material on the side of the material opposite the motor housing. Air drawn in by the fan first passes radially inwardly of the motor housing along the end panel. Air exhausted from the fan passes between the second acoustical panel and the motor housing.