Vibration-induced white finger and auditory susceptibility to noise exposure.

It is well known that there are wide individual variations in the susceptibility of human hearing to noise exposure. The hearing of male forest workers were examined with vibration-induced white finger (VWF) as an indicator of noise susceptibility of hearing. The results were as follows: 1. Hearing losses at 4 and 8 kHz in subjects with VWF were greater than those of unaffected men in a matched pair case-control study allowing for confounding due to differences of age and noise exposure. 2. The hearing loss at 4 kHz on the ipsilateral side of the hand with VWF was greater than the loss on the contralateral side in subjects with VWF in one hand. 3. The hearing loss at 4 kHz in subjects with VWF progressed more rapidly during a five-year follow-up period than the loss in men with no history of VWF. These results indicate that the hearing of subjects with VWF was more vulnerable to noise than the hearing of subjects without VWF. It was suggested that a pathological change causing VWF, such as enhanced vasoconstriction due to elevated sympathetic nervous tone, could also cause this additional auditory vulnerability to noise exposure.