Improvements to the Two-Point In Situ Method for Measurement of the Room Constant and Sound Power in Semi-Reverberant Rooms

Citation data:

Brigham Young University - Provo

Publication Year:
2016
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Repository URL:
https://scholarsarchive.byu.edu/etd/5724; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=6723&context=etd
Author(s):
Jensen, Zachary R
Publisher(s):
Brigham Young University - Provo
Tags:
sound power; room constant; generalized energy density; semi-reverberant enclosure; Astrophysics and Astronomy; Physics
thesis / dissertation description
The two-point in situ method is a technique for measuring the room constant of a semi-reverberant room and the sound power of a source in that room simultaneously using two measurement positions. Using a reference directivity source, where the directivity factor along any given axis of the source has been measured, one is able to use the Hopkins-Stryker equation to measure both the room constant and the sound power level of another source rather simply. Using both numerical and experimental data, it was found that by using generalized energy density (GED) as a measurement quantity, the results were more accurate than those using squared pressure. The results also improved when one measurement position was near the source and the other measurement position was far from the source. This resulted in strong contribution of both the direct and reverberant fields in each of the measurement positions. Another improvement to the two-point method was the use of a local, spatial average around the measurement position. The assumptions in the Hopkins-Stryker equation rely on this average and it was found that a small local spatial average improved the measurements. However, this improvement was greater for squared pressure than for GED. Several source sound power levels and room constants were measured to show that these measurements are improved by using the suggested techniques.