Measurement System for Acoustic Absorption Using the Cepstrum Technique

A measurement system is described for acoustic absorption of automotive carpets and materials using the cepstrum technique. The system is based on prior work by Bolton [1] with modern software and hardware implementation. Time-domain averaging, minimumphase signal generation, late echo removal, and low-frequency data synthesis are implemented using commonly-available commercial hardware and software. The resulting measurement system is capable of making measurements in a normal office environment. Also, the cepstrum technique measurement system can cover a wider frequency spectrum compared to other conventional techniques such as the two-microphone method in an impedance tube or a free field. Results are compared with impedance tube measurements.