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the same noise climate may vary from complete indifference to a state of mind
bordering on desperation. The possibility of a minority disturbance of this sort
may have to be accepted in any general solution of a noise problem, simply because
the economic factors may restrict the solution to something less than complete
insulation.
Noise has been held to be a nuisance if it is an inconvenience materially interfering
with the ordinary physical comfort of human existence according to plain, sober
and simple notions among people.
The main problem of assessing whether or not a noise constitutes a nuisance is due
to the different reactions of people to noise and to the lack of any legal standard.
The Wilson Committee on Noise in its final report suggested, as a very tentative
estimate, that the noise level in a bedroom, at night, in a busy urban area, should
not exceed 35 dBA (decibels—"A" scale) for more than 10 per cent. of the time, nor
exceed 50 dBA during the day. The Building Research Station has given a simplified
procedure for assessing public reaction to industrial noise in a mixed residential and
industrial area. This method, which was referred to in the Wilson Report, suggests
that, if the noise outside the complainant's house exceeds 50-55 dBA, complaints
could be expected. The International Standards Organization has recommended the
use of certain criteria which would suggest that the acceptable level at certain
frequencies would be 35 dBA. The first and last recommendations refer to noise
levels within the building and the Building Research Station's figure, when adjusted
to make allowances for this, is 35-40 dBA.
Noise Measurement
There is, unfortunately, no instrument which will react to noise in the same manner
as the human ear.
The simple noise level meter will show the overall sound pressure level in decibels
at the moment of use. As the "A" scale is said to compare most closely with the
loudness level of the noise, the sound pressure level in dBA is used to make a rough
assessment of the overall sound pressure level at any place. This single figure
reading can, however, be misleading as it gives only the overall sound pressure level
and this overall level is the sum of the noise levels in all the octave bands. The
degree of annoyance varies with the frequency of the noise as well as with the loudness,
high frequency noises being rated as more annoying than low frequency noises of
the same overall loudness, and percussive noises more annoying than steady noises.
Because of these facts, a single dBA reading can give a false impression of the value
of a noise. A noise with a marked high frequency component could give a relatively
low overall level reading on the "A" scale, whereas readings of the sound pressure
levels in the various octave bands would show this high frequency component very
clearly and would give a clear indication of the annoyance likely to be caused by the
noise in question. Data of this nature can only be obtained by employing rather
more sophisticated equipment than is at present available in this Department.
Noise Complaints
During 1965, 102 noise complaints were received in the Department. This figure
is greatly in excess of the total number of complaints received by the three Boroughs
prior to amalgamation and does point to a greater reaction by the public to the
ever growing noise problem.
The complaints varied from noise from traffic on the M.4 motorway to noisy
animals. Just over half of them concerned noise from factories or other industrial
premises and just under half of the total complaints were held to be nuisances. The
investigation of a noise complaint takes a considerable time and often involves the
inspector in a fair measure of work late at night and in the early hours of the morning.
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