1. Dept. of Otorhinolaryngology, Univ. Medical Ctr. Groningen, Univ. of Groningen, PO Box 30.001, Groningen 9700RB, Netherlands,
2. Appl. Linguist, Ctr. for Lang. and Cognition, Univ. of Groningen, Groningen, Netherlands
3. Psych., Univ. of Groningen, Faculty of Behavioural and Social Sci., Groningen, Netherlands