Table 3.

Mean hearing thresholds and 95% confidence interval values for aircraft type and flying time

Aircraft type	Flying hours	Mean (±SD) hearing (dB)	Lower 95% CI	Upper 95% CI
Fixed	<1000	9.84 (±11.76)	7.4	12.2
	1000-1999	11.89 (±20.58)	7.7	16.0
	≥2000	27.50 (±18.44)*	23.7	31.2
Rotary	<1000	8.84 (±5.45)	7.3	10.3
	1000-1999	10.17 (±6.61)	8.3	11.9
	≥2000	23.03 (±11.09)**	20.0	26.0

*P<0.05 for those with ≥2000 flying hours compared with those with 1000-1999 flying hours, **P<0.05 for those with ≥2000 flying hours compared with those with <1000 flying hours. SD – Standard deviation; CI – Confidence interval