A Review of the In Situ Impedance and Sound Absorption Measurement Techniques

This paper presents a review of the literature on the subject of in situ acoustic impedance measurement techniques. The review is intended to be as extensive enough, so that the reader can obtain a broad perspective of the historical evolution of the techniques. Thus, the results of several studies are discussed in order to connect the ideas and insights of many authors and provide an overview of the state of the art technologies in this particular field of acoustics and the path which has led the scientific community to this point. A total of 79 papers are reviewed, 64 of which are directly related to techniques for measuring the surface impedance in situ. Besides a thorough review, a classification scheme for the different methods according to their complexity is also proposed. Finally, some suggestions for future work are given aimed at achieving further advances in the area of in situ impedance measurements.