"Noise, noise sensitivity and psychiatric disorder: epidemiological
and psychophysiological studies.



Academic Department of Psychiatry, University College and Middlesex
School of Medicine, London.

Noise, a prototypical environmental stressor, has clear health
effects in causing hearing loss but other health effects are less
evident. Noise exposure may lead to minor emotional symptoms but the
evidence of elevated levels of aircraft noise leading to psychiatric
hospital admissions and psychiatric disorder in the community is
contradictory. Despite this there are well documented associations
between noise exposure and changes in performance, sleep disturbance
and emotional reactions such as annoyance. Moreover, annoyance is
associated with both environmental noise level and psychological and
physical symptoms, psychiatric disorder and use of health services.
It seems likely that existing psychiatric disorder contributes to
high levels of annoyance. However, there is also the possibility
that tendency to annoyance may be a risk factor for psychiatric
morbidity. Although noise level explains a significant proportion of
the variance in annoyance, the other major factor, confirmed in many
studies, is subjective sensitivity to noise. Noise sensitivity is
also related to psychiatric disorder. The evidence for noise
sensitivity being a risk factor for psychiatric disorder would be
greater if it were a stable personality characteristic, and preceded
psychiatric morbidity. The stability of noise sensitivity and
whether it is merely secondary to psychiatric disorder or is a risk
factor for psychiatric disorder as well as annoyance is examined in
two studies in this monograph: a six-year follow-up of a group of
highly noise sensitive and low noise sensitive women; and a
longitudinal study of depressed patients and matched control
subjects examining changes in noise sensitivity with recovery from
depression. A further dimension of noise effects concerns the impact
of noise on the autonomic nervous system. Most physiological
responses to noise habituate rapidly but in some people
physiological responses persist. It is not clear whether this sub-
sample is also subjectively sensitive to noise and whether failure
to habituate to environmental noise may also represent a biological
indicator of vulnerability to psychiatric disorder. In these studies
noise sensitivity was found to be moderately stable and associated
with current psychiatric disorder and a disposition to negative
affectivity. Noise sensitivity levels did fall with recovery from
depression but still remained high, suggesting an underlying high
level of noise sensitivity. Noise sensitivity was related to higher
tonic skin conductance and heart rate and greater defence/startle
responses during noise exposure in the laboratory. Noise sensitive
people attend more to noises, discriminate more between noises, find
noises more threatening and out of their control, and react to, and
adapt to noises more slowly than less noise sensitive people.
1 year ago"