Impact of nocturnal railway and aircraft noise on awakening probability in the field

Abstract

Objectives: Surveys suggest that railway noise is less annoying than aircraft noise. A study on air, road and rail traffic noise conducted by the DLR-Institute of Aerospace Medicine showed that this order is inversed regarding awakening reactions during sleep in the laboratory. The present study investigated event-related awakening reactions during sleep in a field study on railway noise comparing the results with a similar study on aircraft noise. Methods: 33 healthy participants (mean age 36.2 years ± 10.3 (SD); 22 females) living alongside railway tracks around Cologne/Bonn (Germany) were polysomnographically investigated during nine consecutive nights. The probability of noise-induced awakenings was analysed basing on 8866 recorded noise events. In a second step, these data were pooled with data from a field study on aircraft noise including 64 subjects and 10658 noise events directly comparing the effects of railway and aircraft noise in one model. Results: Probability of sleep stage changes to wake/S1 from railway noise increased significantly from 5.2% at 30 dB(A) to 15.0% at 70 dB(A) LAFmax. Comparing railway noise and aircraft noise, awakening probability decreased in the order freight train noise, aircraft noise, passenger train noise. Conclusions: Nocturnal freight train noise leads to significantly increased awakening probabilities which are higher than for aircraft noise, supporting the order found in the laboratory and contrasting the findings of annoyance surveys. Sound pressure rise time of the noise event proved to be one important factor for explaining different reaction probabilities during sleep.