Community
noise
edited by Birgitta Berglund and Thomas
Lindvall.
Document prepared for WHO.
Archives of the Centre for Sensory
Research, Vol. 2, Issue 1, 1995.
Stockholm University and Karolinska
Institute.
Abstract:
The document critically reviews the adverse effects of community
noise, including interference with communication, noise-induced
hearing loss, annoyance responses, and effects on sleep, the
cardiovascular and psychophysiological systems, performance,
productivity, and social behavior. Noise measures or indices
based only on energy summation are not enough for the
characterization of most noise environments. This is particularly
true when concerned with health assessment and predictions. It is
equally important to measure and display the maximum values of
the noise fluctuations, preferably combined with a measure of the
number of noise events, and to assess whether the noise includes
a large proportion of low frequency components.
For dwellings, recommended guideline values inside bedrooms are
30 dB LAeq for steady-state continuous noise and for a noise
event 45 dB LAmax. To protect the majority of people from being
seriously annoyed during the daytime, the sound pressure level
from steady, continuous noise on balconies, terraces, and in
outdoor living areas should not exceed 55 dB LAeq. To protect the
majority of people from being moderately annoyed during the
daytime, the sound pressure level should not exceed 50 dB LAeq.
At nighttime outdoors, sound pressure levels should not exceed 45
dB LAeq, so that people may sleep with bedroom windows open.
In schools and preschools, to be able to hear and understand
spoken messages in class rooms, the sound pressure level should
not exceed 35 dB LAeq during teaching sessions. For hearing
impaired children, a still lower level may be needed. The
reverberation time in the class room should be about 0.6 s, and
preferably lower for hearing impaired children. For assembly
halls and cafeterias in school buildings, the reverberation time
should be less than 1 s. For outdoor playgrounds the sound
pressure level from external sources should not exceed 55 dB
LAeq.
In hospitals during nighttime, the recommended guideline values
for wardrooms should be 30dB LAeq together with 40 dB LAmax.
Since patients have less ability to cope with stress, the
equivalent soundpressure level should not exceed 35 dB LAeq in
most rooms in which patients are being treated, observed or
resting.
The concern for protecting young people's hearing during leisure
time activities warrants provisional guidelines for concert
halls, outdoor concerts and discotheques. It is recommended that
patrons should not be exposed to sound pressure levels greater
than 100 dB LAeq during a 4-hour period. The same guideline
values apply for sounds played back in headphones when converted
to equivalent free-field level. To avoid hearing deficits from
toys and fireworks, performers and audience should not be exposed
to more than 140 dB(peak) of impulsive sounds. Existing large,
quiet outdoor areas in parkland and conservation areas should be
preserved and the background-to-noise ratio be kept low.
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