Table 3 Mean hearing threshold (dB) at tested audiometry frequencies (Hz) among noise-exposed workers (n = 396) and unexposed workers (n = 210) at two steel factories in Egypt, 2021

Right ear

 Noise-exposed

396

22.52 ± 5.31^a**

22.79 ± 5.09^a**

22.65 ± 5.39^a***

24.14 ± 6.23^a***

31.56 ± 13.9^a***

28.67 ± 11.5^a***

 Unexposed

210

21.40 ± 6.03

21.76 ± 6.08

21.19 ± 5.89

21.54 ± 6.36

22.26 ± 8.66

22.09 ± 8.42

Left ear

 Noise-exposed

396

22.31 ± 5.45^a**

22.32 ± 5.00^a**

22.57 ± 5.51^a***

23.88 ± 6.35^a***

31.06 ± 13.2^a***

28.30 ± 10.8^a***

 Unexposed

210

21.14 ± 5.50

21.21 ± 5.45

21.09 ± 5.96

21.45 ± 6.27

22.14 ± 8.03

22.40 ± 8.38