¹Bruel & Kjaer division of Spectris Co. Ltd., Japan Kita-Shinagawa 1-8-11, Shinagawa, Tokyo, 140-0001, Japan, Mark Allman-Ward

²Sound Evaluations Limited, 18 Walsworth Road, Hitchin, Hertfordshire. UK

³National Institute of Occupational Safety and Health, Japan, Nagao 6-21-1, Tama-ku, Kawasaki 214-8585, Japan