Table 4. Summary of primary heart rate variability according to road traffic noise.

Characteristics	Total (n = 92)	Low road traffic noise (n = 65)	High road traffic noise (n = 27)	F	P value
HR	74.84 ± 7.33	74.53 ± 6.92	75.59 ± 8.33	0.338	0.562
RMSSD	63.24 ± 31.21	65.49 ± 30.51	57.83 ± 32.79	1.234	0.270
NN50	114.97 ± 57.48	120.18 ± 53.49	102.43 ± 65.49	1.619	0.207
pNN50	34.01 ± 18.81	35.74 ± 17.84	29.85 ± 20.73	1.678	0.199
nLF	51.90 ± 13.51	51.91 ± 12.33	51.89 ± 16.28	0.016	0.901
nHF	48.10 ± 13.51	48.09 ± 12.33	48.11 ± 16.28	0.016	0.901
RATIO	1.41 ± 0.79	1.35 ± 0.60	1.55 ± 1.11	0.866	0.355
LF	1,849.78 ± 1,363.30	2,017.46 ± 1,403.13	1,446.09 ± 1,191.34	3.373	0.070
HF	1,830.51 ± 1,916.07	1,991.29 ± 2,047.02	1,443.44 ± 1,521.44	1.673	0.199
TP	9,094.24 ± 6,811.09	9,991.05 ± 7,206.79	6,935.26 ± 5,260.25	3.868	0.052

Data are shown as mean ± standard deviation.

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