Table 4. Mean, standard error and 95% confidence interval adjusted by age and noise exposure levels for ABR results for all three groups of workers.

	Styrene-exposed group		Noise-exposed group		Non-exposed control group
Variable	(n = 98)		(n = 111)		(n = 70)
	Mean (S.E)	95%CI	Mean (S.E)	95% CI	Mean (S.E)	95%CI
Wave I RE	1.73 (.02)	1.69–1.78	1.70 (.03)	1.64–1.76	1.71 (.03)	1.65–1.77
Wave III RE	3.84 (.02)	3.80–3.88	3.88 (.02)	3.82–3.94	3.91 (.02)	3.85–3.96
Wave V RE	5.70 (.03)	5.64–5.76	5.69 (.04)	5.60–5.78	5.82 (.04)	5.74–5.91
I-III IPL RE	2.10 (.02)	2.05–2.15	2.18 (.03)	2.10–2.25	2.19 (.03)	2.12–2.27
I-V IPL RE	3.97(.03)	3.90–4.03	3.99 (.05)	3.89–4.08	4.11 (.05)	4.01–4.21
III-V IPL RE	1.86 (.02)	1.81–1.92	1.80 (.04)	1.73–1.88	1.91 (.04)	1.83–1.99
Wave I LE	1.72 (.01)	1.69–1.76	1.66 (.02)	1.61–1.71	1.73 (.02)	1.68–1.78
Wave III LE	3.84 (.02)	3.80–3.89	3.87 (.03)	3.81–3.93	3.91 (.03)	3.85–3.97
Wave V LE	5.69 (.03)	5.63–5.74	5.65 (.04)	5.56–5.73	5.81 (.04)	5.73–5.90
I-III IPL LE	2.12 (.02)	2.07–2.17	2.20 (.03)	2.13–2.28	2.17 (.03)	2.10–2.25
I-V IPL LE	3.96 (.03)	3.90–4.03	3.98 (.04)	3.88–4.08	4.08 (.04)	3.98–4.17
III-V IPL LE	1.84 (.02)	1.78–1.89	1.77 (.04)	1.69–1.85	1.90 (.04)	1.82–1.98

All values are in milliseconds

RE: right ear; LE: left ear

IPL: Inter-peak latency

S.E: Standard error

95%CI: 95% confidence interval