REPRODUCIBILITY AND APPLICABILITY OF ENSEMBLE AVERAGED SURFACE NORMAL IMPEDANCE OF MATERIALS USING AN IN-SITU TECHNIQUE

This paper investigates by experiment the absorption characteristics of several materials associated with the proposed acoustics impedance method using the combination of sound pressure and particle velocity sensors in various sound fields. This method is based on the concept of "ensemble averaged" surface normal impedance that extends the usage of obtained values to various applications such as architectural acoustics and computational simulations. The measurement technique itself is an improvement of the method using two-microphone technique and diffused ambient noise. A series of measurement in different sound fields was conducted to expand the relevant applicability of in-situ measurement using pu-sensor. The first part of the experiment aimed to confirm the reproducibility of the measured values of the method. Here, comparative round robin measurements in four reverberation rooms were conducted. The general tendencies and discrepancies of ten materials in the various reverberation rooms are discussed. In the second stage, the method was applied with four types of selected materials to examine material???s absorption characteristics at different sound fields such as in architectural spaces. This paper revealed the reliability, applicability and robustness of the method despite the room???s geometrical differences throughout the in-situ measurement