The average hearing level was defined as the mean air-conduction threshold at 500, 1,000, 2,000, and 4,000 Hz.
The average hearing level was 43.1 [+ or -] 17.3 dBHL preoperatively and 39.2 [+ or -] 18.2 dBHL postoperatively.
The average hearing level
was expressed as the average score recorded at five frequencies (250, 500, 1000, 2000, and 4000 Hz, respectively).
The Workplace Safety and Insurance Board (WSIB) in Ontario uses a presbycusis-corrected average hearing level in the speech range (0.5 to 3 kHz) of 26.25 dB as the threshold for granting a pension for NIHL20 which is based on the American Medical Association Guides to the Evaluation of Permanent Impairment.
Thirty-one (18.3%) subjects had a presbycusis-corrected average hearing level in the speech frequencies of >26.25 dB in both ears, which is the level at which a pension would be granted for NIHL by the WSIB in Ontario.
An increase of >15 dB in the average hearing level
(arithmetic mean of 500, 1000, 2000, and 4000 Hz frequencies) was considered as an improvement .
Average hearing levels
are given in dB HL and standard deviations are applied where appropriate.