Performance Validation of the Acoustic Comparison Coupler for the Sound Level Meter Calibration

An acoustic comparison coupler has been designed by the acoustic and vibration research group, National Research and Innovation Agency (BRIN). This research prototype is developed to be utilized by a private and industrial laboratory to comply with periodic tests of a sound level meter (SLM) for frequency weighting as the primary parameter. Further, the performance has been demonstrated in the previous paper. Nevertheless, the comparison test among the acoustic calibration systems associated with this mandatory parameter test has not been conducted yet. Therefore, the purpose of this work is to conduct the validation of this prototype as the SLM calibration system using the two established methods consists of the free field method by using free field facilities and insert voltage technique, and the second method by utilizing the multifunction acoustic calibrator in a pressure field condition. The measurement procedure is carried out following the standard IEC 61672–3. Therefore, the results are compared to the acceptance limit stated by this standard. This work also quantifies the uncertainty measurements that are provided by these methods. From the results, the measured frequency weighting is obtained using these methods. The deviation to the reference values and the expanded uncertainty measurement are also reported.