Three groups were investigated: 1) 20 men who have used a mobile phone frequently and spoken approximately 2 h per day for four years; 2) 20 men who have used a mobile phone for 10-20 minutes per day for four years; and 3) 20 men who have never used a mobile phone (the control group).
The brainstem electric response audiometry data showed no differences between the two experimental groups and the control group.
The data of the pure-tone audiometry also revealed no differences between moderate mobile phone users (group 2) and control subjects. However, detection thresholds in those who talked approximately 2 h per day were found to be higher than those in either moderate users or control subjects.
The results show that a higher degree of hearing loss is associated with long-term exposure to electromagnetic field generated by mobile phones.