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Noise annoyance is a
global phenomenon. A definition of annoyance is "a feeling of
displeasure associated with any agent or condition, known or believed
by an individual or group to adversely affect them" (Lindvall &
Radford 1973; Koelega 1987). However, apart from "annoyance", people
may feel a variety of negative emotions when exposed to community
noise, and may report anger, disappointment, dissatisfaction,
withdrawal, helplessness, depression, anxiety, distraction, agitation,
or exhaustion (Job 1993; Fields et al. 1997 1998). Thus, although the
term annoyance does not cover all the negative reactions, it is used
for convenience in this document.
Noise can produce a
number of social and behavioral effects in residents, besides
annoyance (for review see Berglund & Lindvall 1995). The social and
behavioral effects are often complex, subtle and indirect. Many of the
effects are assumed to be the result of interactions with a number of
non-auditory variables. Social and behavioral effects include changes
in overt everyday behavior patterns (e.g. closing windows, not using
balconies, turning TV and radio to louder levels, writing petitions,
complaining to authorities); adverse changes in social behavior (e.g.
aggression, unfriendliness, disengagement, non-participation); adverse
changes in social indicators (e.g. residential mobility, hospital
admissions, drug consumption, accident rates); and changes in mood
(e.g. less happy, more depressed).
Although changes in
social behavior, such as a reduction in helpfulness and increased
aggressiveness, are associated with noise exposure, noise exposure
alone is not believed to be sufficient to produce aggression. However,
in combination with provocation or pre-existing anger or hostility, it
may trigger aggression. It has also been suspected that people are
less willing to help, both during exposure and for a period after
exposure. Fairly consistent evidence shows that noise above 80 dBA is
associated with reduced helping behavior and increased aggressive
behavior. Particularly, there is concern that high-level continuous
noise exposures may contribute to the susceptibility of schoolchildren
to feelings of helplessness (Evans & Lepore 1993)
The effects of
community noise can be evaluated by assessing the extent of annoyance
(low, moderate, high) among exposed individuals; or by assessing the
disturbance of specific activities, such as reading, watching
television and communication. The relationship between annoyance and
activity disturbances is not necessarily direct and there are examples
of situations where the extent of annoyance is low, despite a high
level of activity disturbance. For aircraft noise, the most important
effects are interference with rest, recreation and watching
television. This is in contrast to road traffic noise, where sleep
disturbance is the predominant effect (Berglund & Lindvall 1995).
A number of studies
have shown that equal levels of traffic and industrial noises result
in different magnitudes of annoyance (Hall et al. 1981; Griffiths
1983; Miedema 1993; Bradley 1994a; Miedema & Vos 1998). This has led
to criticism (e.g. Kryter 1994; Bradley 1994a) of averaged
dose-response curves determined by meta-analysis, which assumed that
all traffic noises are the same (Fidell et al. 1991; Fields 1994a;
Finegold et al. 1994). Schultz (1978) and Miedema & Vos (1998) have
synthesized curves of annoyance associated with three types of traffic
noise (road, air, railway). In these curves, the percentage of people
highly or moderately annoyed was related to the day and night
continuous equivalent sound level, Ldn. For each of the
three types of traffic noise, the percentage of highly annoyed persons
in a population started to increase at an Ldn value of 42
dBA, and the percentage of moderately annoyed persons at an Ldn
value of 37 dBA (Miedema & Vos 1998). Aircraft noise produced a
stronger annoyance response than road traffic, for the same Ldn
exposure, consistent with earlier analyses (Kryter 1994; Bradley
1994a). However, caution should be exercised when interpreting
synthesized data from different studies, since five major parameters
should be randomly distributed for the analyses to be valid: personal,
demographic, and lifestyle factors, as well as the duration of noise
exposure and the population experience with noise (Kryter 1994).
Annoyance in
populations exposed to environmental noise varies not only with the
acoustical characteristics of the noise (source, exposure), but also
with many non-acoustical factors of social, psychological, or economic
nature (Fields 1993). These factors include fear associated with the
noise source, conviction that the noise could be reduced by third
parties, individual noise sensitivity, the degree to which an
individual feels able to control the noise (coping strategies), and
whether the noise originates from an important economic activity.
Demographic variables such as age, sex and socioeconomic status, are
less strongly associated with annoyance. The correlation between noise
exposure and general annoyance is much higher at the group level than
at the individual level, as might be expected. Data from 42 surveys
showed that at the group level about 70% of the variance in annoyance
is explained by noise exposure characteristics, whereas at the
individual level it is typically about 20% (Job 1988).
When the type and
amount of noise exposure is kept constant in the meta-analyses,
differences between communities, regions and countries still exist
(Fields 1990; Bradley 1996). This is well demonstrated by a comparison
of the dose-response curve determined for road-traffic noise (Miedema
& Vos 1998) and that obtained in a survey along the North-South
transportation route through the Austrian Alps (Lercher 1998b). The
differences may be explained in terms of the influence of topography
and meteorological factors on acoustical measures, as well as the low
background noise level on the mountain slopes.
Stronger reactions have
been observed when noise is accompanied by vibrations and contains low
frequency components (Paulsen & Kastka 1995; Öhrström 1997; for review
see Berglund et al. 1996), or when the noise contains impulses, such
as shooting noise (Buchta 1996; Vos 1996; Smoorenburg 1998). Stronger,
but temporary, reactions also occur when noise exposure is increased
over time, in comparison to situations with constant noise exposure
(e.g. HCN 1997; Klæboe et al. 1998). Conversely, for road traffic
noise, the introduction of noise protection barriers in residential
areas resulted in smaller reductions in annoyance than expected for a
stationary situation (Kastka et al. 1995).
To obtain an indicator
for annoyance, other methods of combining parameters of noise exposure
have been extensively tested, in addition to metrics such as LAeq,24h
and Ldn. When used for a set of community noises, these
indicators correlate well both among themselves and with LAeq,24h or Ldn
values (e.g. HCN 1997). Although LAeq,24h and Ldn are in
most cases acceptable approximations, there is a growing concern that
all the component parameters of the noise should be individually
assessed in noise exposure investigations, at least in the complex cases
(Berglund & Lindvall 1995). |
