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. 2018 Jul 25;10(1):109–113. doi: 10.1016/j.shaw.2018.07.002

Table 2.

The effect of various SPLs on participants' cortisol concentrations in the three data collection times

Time intervals Group Group Mean difference Std. error p
11–11:30 PM SPL1 = 67 dBA SPL2 = 80 dBA −2.60 .91 0.01
SPL3 = 92 dBA −5.80 .91 <0.0001
SPL2 = 80 dBA SPL3 = 92 dBA −3.20 .91 0.002
2–2:30 AM SPL1 = 67 dBA SPL2 = 80 dBA −1.80 .83 0.10
SPL3 = 92 dBA −4.40 .83 <0.0001
SPL2 = 80 dBA SPL3 = 92 dBA −2.60 .83 0.008
5–5:30 AM SPL1 = 67 dBA SPL2 = 80 dBA −1.32 .54 0.06
SPL3 = 92 dBA −3.80 .54 <0.0001
SPL2 = 80 dBA SPL3 = 92 dBA −2.48 .54 <0.0001

SPL, sound pressure level.