LAUSR

Abstract In this study, we demonstrated the practicability of an ensemble averaging method: EA pu method using pressure-velocity sensors (pu-sensors) to measure the absorption coefficient and surface normal impedance of materials. Improvements in pu-sensor calibration and evaluation of the reproducibility of EA pu method in three reverberation rooms with consideration of humidity have been previously described. The improved geometrical configurations for pu-sensor calibration enables raising the measurable frequency upper limit of the EA pu method from 1500 to 3000 Hz; however, uncertainty remains at low frequencies. Herein, we performed an experiment at low frequencies in a reverberation room using mode analysis and proposed trial applications using moving sound sources and absorbing panels. We then conducted a series of examinations using the EA pu method with the improved pu-sensor calibration in five in situ sound fields to validate the reproducibility of measuring the absorption characteristics of glass wool and needle felt. Even for a large variety of sound fields, the results of this study demonstrate excellent agreement of absorption characteristic values among five practical sound fields in the frequency range 200–2500 Hz in 1/3 octave band mean values. These results reaffirm the wide practicability of the EA pu method with robustness and feasibility.