Table 1. Demographic and socioeconomic variables of subjects according to road traffic noise.
| Characteristics | Total (n = 474) | Low road traffic noise (n = 361) | High road traffic noise (n = 113) | t-test or χ2 test | |
|---|---|---|---|---|---|
| Age, yr | 10.01 ± 0.31 | 10.01 ± 0.30 | 10.02 ± 0.33 | 0.730 | |
| Sex | 0.640 | ||||
| Boy | 223 (47.0) | 172 (47.6) | 51 (45.1) | ||
| Girl | 251 (53.0) | 189 (52.4) | 62 (54.9) | ||
| Monthly income, won | 0.969 | ||||
| < 5 million | 211 (45.4) | 160 (45.3) | 51 (45.5) | ||
| ≥ 5 million | 254 (54.6) | 193 (54.7) | 61 (54.5) | ||
| Low birth weighta | 19 (4.0) | 8 (2.2) | 11 (9.7) | ||
| Premature birtha | 24 (5.1) | 14 (3.9) | 10 (8.8) | ||
| Maternal age at birth, yr | 30.60 ± 3.53 | 30.60 ± 3.54 | 30.62 ± 3.50 | 0.953 | |
| Passive smoking | 71 (15.0) | 55 (15.3) | 16 (14.2) | 0.763 | |
| Maternal illness during pregnancya | |||||
| Diabetes | 8 (1.7) | 7 (1.9) | 1 (0.9) | ||
| Hypertension | 5 (1.1) | 4 (1.1) | 1 (0.9) | ||
| Preeclampsia | 17 (3.6) | 12 (3.3) | 5 (4.4) | ||
| Thyroid disease | 9 (1.9) | 9 (2.5) | 0 (0.0) | ||
| Mental disordersa | |||||
| ADHD | 8 (1.7) | 8 (2.2) | 0 (0.0) | ||
| Specific learning disorder | 6 (1.3) | 4 (1.1) | 2 (1.8) | ||
| Communication disorder | 9 (1.9) | 8 (2.2) | 1 (0.9) | ||
| Intellectual disability | 2 (0.4) | 2 (0.6) | 0 (0.0) | ||
| Autism spectrum disorder | 2 (0.4) | 2 (0.6) | 0 (0.0) | ||
| Motor disorder | 7 (1.5) | 5 (1.4) | 2 (1.8) | ||
| Depression | 3 (0.6) | 3 (0.8) | 0 (0.0) | ||
| Conduct disorder | 2 (0.4) | 2 (0.6) | 0 (0.0) | ||
| Noise level, dBA, Ldn | 56.03 ± 10.20 | 53.71 ± 9.32 | 68.74 ± 2.79 | < 0.001*** | |
| NS | 3.24 ± 1.95 | 3.29 ± 1.93 | 3.05 ± 1.98 | 0.252 | |
Data are shown as mean ± standard deviation or number (%).
ADHD = attention deficit and hyperactivity disorder, NS = noise sensitivity.
aχ2 test was not performed for the value of which each cell was less than 5.
***P < 0.001.