[1] Natl. Inst. for Working Life/West, P.O. Box 8850, 402 Göteborg, Sweden
[2] Department of Occupational Medicine, Sahlgrenska Academy, Göteborg University, Göteborg, Sweden
[3] Department of Audiology, Sahlgrenska Academy, Göteborg University, Göteborg, Sweden
[4] Plejadgatan 3, 402 72 Göteborg, Sweden