Construction of Two Anechoic Rooms with a New Experimental Floor Structure

This paper introduces new acoustic experimental facility consisting of two anechoic rooms designed for different purposes. One is a large anechoic room (LDH = 7.0x8.5x6.0 m) outfitted with 1050 mm sound absorbing wedges made of a polyester nonwoven fabric and moderate electromagnetic shielding (>40 dB). Wedges in two different shapes were used to attain a cut-off frequency of 63 Hz, and to expand the acoustic free field in terms of ISO 3745. Residual noise level does not exceed 3 dB (overall) and -8 dB at 1 kHz (1/3 oct.) during normal air conditioning operation. The second anechoic room is smaller (4.5x3.9x4.1 m) and uses 325 mm wedges while having good electromagnetic shielding (>100 dB). This room is designed for multisensory research, and is equipped with a linear motor device embedded in the floor. This device can move quietly at high speeds and is used to generate vestibular inputs. Both rooms use a new walking floor structure that can achieve both, low acoustic reflectivity and good usability. This paper introduces these rooms, with special attention given to the design and performance of the new walking floor structure when compared to a conventional one.