快猫短视频

CHILDREN can be stressed out by everyday noise at levels too low to damage
their hearing, according to research in the US and Austria. Chronic exposure to
nearby sounds such as roads and train lines could also create problems with
motivation.

The study, commissioned by the Austrian Ministry of Health, found that
children living in relatively noisy neighbourhoods had raised blood pressure,
heart rates and levels of stress hormones. 鈥淣on-auditory effects of noise appear
to occur at levels far below those required to damage hearing,鈥� says Peter
Lercher of the Institute of Social Medicine at the University of Innsbruck,
Sonnenburgstrasse, who carried out the study with Gary Evans from Cornell
University in Ithaca, New York.

鈥淲e are really not looking at loud kinds of noise. They are typical levels
found throughout neighbourhoods in Europe,鈥� says Evans. 鈥淚t suggests that
children living in noisier areas of residential communities are subject to
蝉迟谤别蝉蝉.鈥�

We don鈥檛 know much about the non-auditory health effects of exposure to
everyday noise at lower intensity, says Evans. Previous research has focused on
what happens to hearing when people live near excessively loud noise from
airports or high-speed rail lines, for example. This is the first study to
examine the stressful effects of low-intensity noise.

Evans and Lercher took 115 nine and ten-year-olds from alpine villages in the
Inn Valley region of Tyrol in Austria and divided them into two groups: those
living in neighbourhoods with noise levels of less than 50 decibels and those
with levels higher than 60 decibels. They tested each child鈥檚 blood pressure,
heart rate, and cortisol and adrenalin levels while they were resting.

Background noise had a significant effect on stress levels, says Lercher. The
researchers want to know how this affects children鈥檚 health in the long term.
鈥淎nything that increases blood pressure over time is something to worry about,鈥�
says Evans.

Questionnaires and motivation tasks also revealed that this kind of stress
could weaken a child鈥檚 motivation. Prolonged exposure to noise that children
have no control over appears to lead to 鈥渓earned helplessness鈥� syndrome, the
researchers report. The same condition has previously been linked to forms of
depression and to poverty. 鈥淚t鈥檚 a pretty pervasive phenomenon,鈥� says Evans.
鈥淕irls in particular seem to be a little bit more vulnerable to learned
丑别濒辫濒别蝉蝉苍别蝉蝉.鈥�

According to John Stewart, chairman of the UK Noise Association in London,
the research confirms anecdotal evidence from people living under flight paths
that prolonged exposure to noise levels within safety limits can still be bad
for your health. This is precisely the kind of issue that governments have
failed to acknowledge for years, he says. 鈥淲hat they really refuse to look at
are lower levels of noise that is fairly constant,鈥� says Stewart.