Stephen P. Rittmueller - St. Charles IL J. Adin Mann - Ames IA David K. Holger - Ames IA Douglas E. Johnson - Webster City IA
Assignee:
Iowa State University Research Foundation, Inc. - Ames IA White Consolidated Industries, Inc. - Cleveland OH
International Classification:
A47L 900
US Classification:
15326
Abstract:
A central vacuum cleaner having an air flow exhaust pipe is provided with a muffler comprising an elongated muffler pipe having a reduced diameter inlet and a reduced diameter outlet and a noise reducing foam liner disposed in the muffler pipe between the inlet and outlet. The foam liner includes a smooth inner surface that is generally flush with inner surfaces of the inlet and outlet. The foam liner comprises a combustion modified polyether polyurethane foam tube inserted in the muffler pipe between the inlet and outlet.
Iowa State University Research Foundation, Inc. - Ames IA
International Classification:
G01N 2900
US Classification:
73646
Abstract:
Sound intensity is determined by simultaneously measuring instantaneous acoustic pressure and instantaneous particle velocity at a single point. A condenser microphone having a vibrating diaphragm generates an output voltage proportional to the instantaneous acoustic pressure. A laser Doppler vibrometer measures the velocity of the vibrating diaphragm and a Doppler frequency tracker converts the velocity measurement into another output voltage which is proportional to the instantaneous acoustic particle velocity. The sound intensity is then calculated from the known components.