Time Assessment on Sensor Stability for Sound Absorption Measurement

Abstract

In previous study, humidity consistency had been proven as significant contributor to the stability of sensor in measuring absorption coefficient of acoustical material. This phenomenon becomes critical as method of in-situ measurements naturally involve environmental variables, where temperature and humidity may vary. This research applies two similar pu-sensors (pu-1 and pu-2) in series of calibration and EA-method measurement sets then comparing both results on absorption characteristics through standard deviations, each in various controlled humidity. In every of four measurement sets, both sensors behave in similar trend in responding different humidity changes, Dj. The higher the humidity difference, Djbetween measurement sets, the bigger deviation of results occurred. To confirm this humidity effects on sensors’ stability on measurement of absorption coefficient by EA-method, further investigation were performed by statistical correlation between humidity levels and the time of measurements (4 sets of separated time). Environment humidity manually controlled in ranges of 30 - 60% by set of fans and humidifiers throughout set of measurement, while deeper understanding on the resulted deviations were discussed by evaluation on the sensors working principles and how its sensibility may effected by humidity in the environment.  Based on time and humidity difference, Dj  statistical simulation, correlation between sensor’s calibrations and their responses in 4 separated time of experiments had emphasized the above phenomenon. No significant differences on both sensors’ deviation in each of the experiment time sets, leaving humidity as the deviation source with less correlation to time of measurements.