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Full-Text Articles in Physical Sciences and Mathematics
Generalized Acoustic Energy Density And Its Applications, Buye Xu
Generalized Acoustic Energy Density And Its Applications, Buye Xu
Theses and Dissertations
The properties of acoustic kinetic energy density and total energy density of sound fields in lightly damped enclosures have been explored thoroughly in the literature. Their increased spatial uniformity makes them more favorable measurement quantities for various applications than acoustic potential energy density (or squared pressure), which is most often used. In this dissertation, a new acoustic energy quantity, the generalized acoustic energy density (GED), will be introduced. It is defined by introducing weighting factors, α and 1 − α, in the formulation of total acoustic energy density. With the additional degree of freedom, the GED can conform to the …
Sound Absorption And Sound Power Measurements In Reverberation Chambers Using Energy Density Methods, David B. Nutter
Sound Absorption And Sound Power Measurements In Reverberation Chambers Using Energy Density Methods, David B. Nutter
Theses and Dissertations
Measurements in a reverberation chamber use spatially averaged squared pressure to calculate sound absorption, sound power, and other sound measurements. While a reverberation chamber provides an approximation of a diffuse sound field, variations in the measurements introduce uncertainty in measurement results. Room qualification procedures require a sufficient number of source-receiver locations to obtain suitable measurements. The total acoustic energy density provides greater spatial uniformity than squared pressure, which requires fewer source-receiver positions to produce similar or better accuracy in measurement results. This paper explores the possibility of using energy density in place of squared pressure, using methods outlined in current …
Active Minimization Of Acoustic Energy Density In A Mock Tractor Cab, Benjamin Mahonri Faber
Active Minimization Of Acoustic Energy Density In A Mock Tractor Cab, Benjamin Mahonri Faber
Theses and Dissertations
An active noise control (ANC) system has been applied to the problem of attenuating low-frequency tonal noise inside small enclosures. The intended target application of the system was the reduction of the engine firing frequency inside heavy equipment cabins. The ANC system was based on a version of the filtered-x LMS adaptive algorithm, modified for the minimization of acoustic energy density (ED), rather than the more traditional minimization of squared acoustic pressure (SP). Three loudspeakers produced control signals within a mock cabin composed of a steel frame with plywood sides and a Plexiglas® front. An energy density sensor, capable of …