Hearing in 55 to 75 year old people in northern Finland--a comparison of two classifications of hearing impairment.

A total of 5,400 persons from different age groups was randomly selected from the population register for the study, and of the 1,620 55 to 75 year old persons invited, 1,233 attended the check-ups (76.1%). Air conduction pure tone thresholds were measured at the frequencies of 0.25, 0.5, 1, 2, 3, 4, 6 and 8 kHz. The findings were interpreted according to both the EU and WHO classifications. According to the WHO classification, 1,046 subjects (85.0%) had normal hearing and 124 persons (10.1%) had a mild hearing impairment, 44 (3.6%) a moderate, 13 (1.1%) a severe and 3 (0.2%) had a profound hearing impairment. According to the EU classification, 758 subjects (61.6%) were found to have normal hearing, a mild impairment was observed in 363 persons (29.5%), a moderate hearing impairment in 96 (7.8%) and a severe impairment in 13 (1.1%) persons. None had a profound hearing impairment. The difference between these classifications is remarkable as is evident in even this small study. A thorough discussion on the role of different gradings for hearing is needed.