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Reaction to noise is governed not only by loudness, but by the type of noise,
i.e. its frequency. If a noise is confined to a narrow waveband, so that the sound is on
a fairly definite pitch, it is much more intrusive than a sound of mixed frequencies.
As a result, the whine from a fan motor or ventilating duct may be a source of
complaint, although the actual level of noise is comparatively low, and conditions
will be aggravated if the appliance operates twenty-four hours a day. Such complaints
often require investigation during the evening or even during the night to establish
the source of the noise and the sound level in relation to background noise.
There is no universal cure for noise nuisance. Each case must be considered
individually, for in addition to abating the nuisance, any work carried out must be
compatible with the operation of the plant. With established machinery, this is often
difficult and expensive. More consideration should be given to the question of noise
when new equipment or factories are planned, and there is much to be said in favour
of prior approval of potential sources of noise.
One case involved new air extraction plant installed in an existing factory in
close proximity to dwelling houses. The noise from this brought complaints from a
number of residents. These complaints were fully justified, and after long negotiation
with the firm concerned, silencers were designed and fitted to the extraction plant.
This resulted in the noise level at the houses being reduced by 10 dBA; in common
parlance, the noise was cut by half. A great deal of time, money and inconvenience
could have been saved if the question of noise in relation to adjoining buildings had
been considered before the plant was installed, and an alternative position for the
extractors would probably have avoided any complaints.
In recent years there have been a number of complaints of noise and vibraition
from self-service launderettes which operate till late evening or throughout the night.
Every endeavour is now made to see this type of premises when installation is in
progress, and to ensure that machines, pipe work and pumps are efficiently insulated
or isolated.
A more recent development is the installation of cold store motor rooms, for
supermarkets, in the roofs of the buildings. Motor and fan noise has already proved
to be a nuisance to adjoining householders during the night, and remedial measures
were necessary on two installations during 1969.
The Council includes a condition in its contracts requiring the use of mufflers
on all pneumatic drills used on Council work, and the public utility undertakings
have agreed to do the same. Mufflers do make some improvement but the noise from
pneumatic drills is resented by householders, shopkeepers and everyone within range
of their operation. There is a great need for an alternative method of breaking
concrete and opening up roads which will at the same time be efficient, economic and
acceptable to the public.
During the year 885 visits were made in connection with noise complaints and
an encouraging feature was the degree of co-operation from those responsible for
the operation of machinery and plant. It may not be possible to eliminate noise
completely, but every effort is made to have it reduced to a reasonable level.
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