Recently, sound absorption characteristics of materials have become of more importance for broad range of acoustics, especially for data-driven-room-acoustics. The authors proposed a measurement method using the ensemble averaging technique for sound absorption characteristics, i.e., surface impedance and sound absorption coefficient; and we name the method EA-method, for short. Originally, the frequency range of the EA-method is targeted from 100 to 1500 Hz, and, afterword, it is extended from 100 to 3000 Hz. However, a room's acoustics in the lower frequency region, such as below 100 Hz, becomes non-negligible or of more importance, nowadays. Herein, an improvement of pu-sensor calibration is applied and results of trial measurements are presented. Since the major target of the EA-method is in-situ applications at practical building environments, a simple, light and efficient system is indispensable. Several case studies at practical measurements show the effectiveness of the improvement.
Otsuru et al. (Wed,) studied this question.