PubMed1990
In a group of 126 men the authors evaluated the auditory threshold from cortical ERA findings and comparison with their threshold sound audiometry. The mean age of the patients means = 52.5 years (min. = 25 years, max. = 69 years, s = 8.95). Noise exposure means = 16.5 years (min. = 4 years, max. = 30 years, s = 4.5). In 79.3% the men worked as miners in uranium mines, other mining occupations were represented only by small numbers. The arithmetic mean of the total percentage hearing loss (calculated according to Fowler) means = 49.7% (min. = 17%, max. = 100%, s = 15). The cumulative frequency of differences between the auditory threshold of the sound audiogram and cortical ERA: (table; see text) The cumulative frequency of differences in the total percentage hearing loss between sound audiograms and cortical ERA: differences up to +/- 5% hearing loss were recorded in 24.3% of the group, differences up to +/- 10% in 43.9%, differences up to +/- 15% in 58.9%, differences up to +/- 20% in 70.1%. In the group of 126 examined subjects we detected 12 aggravating subjects (9.5%), their mean age being by 6.7 years lower than the mean of the whole group, the mean exposure to noise is by 3.2 years shorter. The differences between the auditory threshold reported by the aggravating men and the cortical ERA are highest in verbal frequencies, on average they are per fr of 2 kHz 27.3 dB, 1 kHz 24.3 dB, 0.5 kHz 20.1 dB, 4 kHz, 10.0 dB. The differences between the total percentage auditory loss calculated from sound audiograms and cortical ERA reaches on average 41.5%.