E. Ohrstrom, EFFECTS OF LOW-LEVELS OF ROAD TRAFFIC NOISE DURING THE NIGHT - A LABORATORY STUDY ON NUMBER OF EVENTS, MAXIMUM NOISE-LEVELS AND NOISE SENSITIVITY, Journal of sound and vibration, 179(4), 1995, pp. 603-615
The objective of the laboratory study presented here was to elucidate
the importance of the number of noise events of a relatively low maxim
um noise level for sleep disturbance effects (body movements, subjecti
ve sleep quality, mood and performance). Twelve test persons slept eig
ht nights under home-like laboratory settings. During four of these ni
ghts, each test person was exposed to 16, 32, 64 and 128 noise events
respectively from recorded road traffic noise at a maximum noise level
of 45 dB(A). All test persons (aged 20-42 years) considered themselve
s rather or very sensitive towards noise. The results show a significa
nt decrease in subjective sleep quality at 32 noise events per night,
At 64 noise events, 50% of the test persons experienced difficulties i
n falling asleep and, as compared with quiet nights, the time required
to fall asleep was on average 12 minutes longer. The occurrence of bo
dy movements was significantly related to the reported number of awake
nings, and the number of body movements was three times higher during
the noisy periods of the night as compared with the quiet periods, ind
icating acute noise effects. The results of a vigilance test indicate
that noise during the night might prolong the time needed to solve the
test. Finally, and regardless of number of noise events, a significan
t increase in tiredness during the day was found after nights with noi
se exposure. In the paper comparisons are also made with earlier exper
iments using maximum noise levels of 50 and 60 dB(A).