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Table 3 Cases of hypertension and associated exposure to different noise frequencies

From: Road traffic noise frequency and prevalent hypertension in Taichung, Taiwan: A cross-sectional study

Characteristics Case group (n = 46) Control group (n = 774) Total subjects (n = 820) P-value
LAeq 8 h (dBA)     
 Median (Q1, Q3) 81 (79, 82) 79 (77, 82) 79 (77, 82) 0.016a
Frequency components    
31.5 Hz (dB)     
 Median (Q1, Q3) 29 (26, 31) 27 (25, 30) 27 (25, 30) 0.222a
63 Hz (dB)     
 Median (Q1, Q3) 43 (41, 45) 41 (38, 44) 41 (38, 44) 0.026a
125 Hz (dB)     
 Median (Q1, Q3) 50 (48, 52) 49 (47, 51) 49 (47, 51) 0.032a
250 Hz (dB)     
 Median (Q1, Q3) 55 (53, 56) 54 (52, 55) 54 (53, 55) 0.017a
500 Hz (dB)     
 Median (Q1, Q3) 58 (57, 60) 58 (56, 59) 58 (56, 59) 0.032a
1000 Hz (dB)     
 Median (Q1, Q3) 61 (60, 63) 61 (59, 63) 61 (59, 63) 0.070a
2000 Hz (dB)     
 Median (Q1, Q3) 59 (57, 61) 59 (57, 61) 59 (57, 61) 0.120a
4000 Hz (dB)     
 Median (Q1, Q3) 57 (54, 58) 56 (53, 59) 56 (53, 59) 0.458a
8000 Hz (dB)     
 Median (Q1, Q3) 50 (48, 52) 49 (45, 52) 49 (45, 52) 0.096a
  1. dB = decibel; dBA = A-weighted decibel; LAeq 8 h = A-weighted equivalent sound level at 09:00–17:00; Q1 = first quartile; Q3 = third quartile. aWilcoxon signed rank sum test of the difference between the two groups.