Table 11. Summary of heart rate variability according to noise level, stratified by NS (high NS).

Characteristics	High NS (road traffic) (n = 29)		F	P value	High NS (aircraft) (n = 13)		F	P value
	Low noise (n = 22)	High noise (n = 7)			Low noise (n = 7)	High noise (n = 6)
HR	73.91 ± 7.47	75.76 ± 10.10	0.145	0.707	73.70 ± 7.70	72.80 ± 7.20	0.059	0.814
RMSSD	67.33 ± 19.65	70.13 ± 37.68	0.099	0.755	61.58 ± 15.20	83.79 ± 18.63	1.508	0.248
SDSD	0.07 ± 0.02	0.07 ± 0.04	0.043	0.837	0.06 ± 0.02	0.09 ± 0.02	1.579	0.238
NN50	134.34 ± 41.27	110.03 ± 54.86	1.178	0.288	125.11 ± 36.11	163.74 ± 28.97	0.252	0.626
pNN50	40.06 ± 14.08	32.39 ± 18.15	1.008	0.325	37.30 ± 12.76	48.94 ± 11.54	0.087	0.774
LF	2,261.81 ± 1,098.48	1,824.62 ± 1,046.63	0.868	0.360	2,047.82 ± 1,047.31	2,389.75 ± 291.75	4.290	0.065
HF	1,986.71 ± 1,146.04	1,647.58 ± 1,140.47	0.271	0.607	1,533.97 ± 663.99	2,873.16 ± 1,404.82	2.162	0.172
TP	10,779.11 ± 5,496.63	8,864.14 ± 6,445.37	0.414	0.525	7,734.91 ± 3,305.36	13,724.08 ± 3,835.76	7.328	0.022*
RATIO	1.35 ± 0.64	1.36 ± 0.78	0.009	0.927	1.48 ± 0.74	1.04 ± 0.47	0.009	0.927
nLF	52.21 ± 13.78	52.74 ± 11.93	0.002	0.966	52.63 ± 18.55	47.95 ± 11.83	0.632	0.445
nHF	47.79 ± 13.78	47.26 ± 11.93	0.002	0.966	47.37 ± 18.55	52.05 ± 11.83	0.632	0.445

Data are shown as mean ± standard deviation.

NS = noise sensitivity, HR = heart rate, RMSSD = root mean square of successive difference of successive normal-to-normal, SDSD = standard deviation of successive differences, NN50 = difference between adjacent normal-to-normal intervals of 50 ms or more, pNN50 = NN50/total number of all normal-to-normal, LF = power in low-frequency range, HF = power in high-frequency range, TP = total power, RATIO = LF/HF ratio, nLF = low-frequency power in normalized units, nHF = high-frequency power in normalized units.

^*P < 0.05.