1. Finnish Institute of Occupational Health; Cochrane Occupational Health Field, Team of Knowledge Transfer in Occupational Health and Safety; PO Box 310 (Neulaniementie 4) Kuopio Finland 70101
2. Motivoice Ltd; Espoo Finland
3. Helsinki Central Hospital; Phoniatrics Department, ENT Clinic; P.O.Box 220 Helsinki Finland 00029 HUCH
4. Finnish Institute of Occupational Health; Topeliuksenkatu 41aA Helsinki Finland FI-00250