Construction of two anechoic rooms with a new experimental floor structure

This paper introduces a new acoustic experimental facility consisting of two anechoic rooms designed for different purposes. One is a large anechoic room (LDH = 7.0 x 8.5 x 6.0 m) outfitted with 1.05 m sound-absorbing wedges made of a nonwoven polyester fabric backed by moderate electromagnetic shielding (>30 dB). Wedges in two shapes were used to attain a cut-off frequency of 63 Hz and to expand the acoustic-free field in terms of ISO 3745 (1). The residual noise level does not exceed 3 dB (overall) and -8 dB at 1 kHz (1/3 oct.) during normal air-conditioning operations. The second anechoic room, which is smaller (4.5 x 3.9 x 4.1 m), uses 0.325 m wedges while providing good electromagnetic shielding (>100 dB). This room, designed for multisensory research, is equipped with a linear motor device embedded in the floor. This device can move quietly at high speeds. It is used to generate vestibular inputs. Both rooms use a new walking floor structure that can achieve low acoustic reflectivity and good usability. This paper introduces these rooms, with special attention devoted to the design and performance of the new walking floor structure when compared to a conventional one.