. Author manuscript; available in PMC: 2015 Sep 15.

Published in final edited form as: J Occup Environ Hyg. 2011 May;8(5):310–323. doi: 10.1080/15459624.2011.568832

TABLE II.

Noise Exposures at the Work Shift Level Overall and by Trade and Subjective (SR) Item Responses for Internal (i.e., Study) and External (i.e., Non-Study) Sites

Variable	Internal (three sites)			External (one site)^A			Diff. (dBA)
Variable	n	Mean L_EQij (dBA)	SD L_EQ (dBA)	n	Mean L_EQij (dBA)	SD L_EQ (dBA)	Diff. (dBA)
Measured exposure	204	88.8	4.3	19	90.2	3.0	−1.4
SR Perceived Intensity Items
Noise frequency	204			19
Never	8	81.7^B	6.1	3	85.7	4.1	−4.0
Sometimes	185	88.9^B	4.0	15	91.8	3.8	−2.9
Always	11	91.8^B	4.0	1	92.9	—	1.1
Raise voice	204			19
Never	21	87.0	6.2	3	90.1	7.5	−3.1
Sometimes	174	88.9	4.1	13	91.6	3.7	−2.7
Always	9	90.9	3.5	3	93.0	2.8	−2.1
Percent time in noise	204			19
Speaking voice	97	87.1^B	4.2	7	90.7	5.6	−3.6
Vacuum-chainsaw	78	89.0^B	2.9	9	91.6	3.0	−2.7
Siren	29	93.9^B	4.1	3	94.6	2.2	−0.7
SR Perceived Variability Items
	n^B	Mean L_MAX/L_EQij	SD L_MAX/L_EQij	n	Mean L_MAX/L_EQij	SD L_MAX/L_EQij	Diff. (dBA)
Noise bursts	204
Never	11	52.0^C	29.7	—	—	—
Sometimes	187	60.4^C	18.3	13	56.6^C	8.2	3.8
Always	6	135.8^C	36.7	6	64.7^C	5.6	71.1
	n	Mean L_EQ/L_AVGij	SD L_EQ/L_AVGij	n	Mean L_EQ/L_AVGij	SD L_EQ/L_AVGij	Diff.
Noise variability	204
Usually steady	68	2.2^C	0.7	6	2.0	0.1	0.2
Usually variable	136	2.7^C	1.2	13	2.1	0.3	0.6
	n	Mean L_EQij SD	SD Mean L_EQij SD	n	Mean L_EQij SD	SD Mean L_EQij SD	Diff. (dBA)
Task variability	204
Usually same	107	2.3^C	1.4	—	—	—	—
Usually changing	97	3.3^C	2.6	—	—	—	—

Note: n = three measurements each on 68 subjects.

Source, Reference 1.

Significant trend across response categories (Cuzik’s test for trend, p < 0.05).

Significant difference in levels across response categories (one-way ANOVA, p < 0.05).