48 SECTIONAL ADDRESSES 



both new and old, representing all the main types on the roads to-day. 

 The results (at a distance of i8 feet sideways or 25 feet to the rear) mostly 

 ranged between about 70 and 105 phons (the latter value corresponding 

 to a noisy road drill). The Committee were led to propose simple 

 running and racing engine tests which are associated, under specified 

 conditions, with an ' over-all ' noise limit of 95 phons, which is roughly 

 equivalent to the noise in a tube train) for all vehicles in use on the road, 

 and of 90 phons for new vehicles leaving manufacturer's works. 



The adoption of these noise limits, while making very moderate demands 

 on most types of vehicles would, by ruling out the arch offenders, constitute 

 a substantial contribution to the amenities of the road. In the meantime, 

 the industry, which has already discovered that ' silence is saleable,' has the 

 matter well in hand and indeed it is not unlikely that future developments 

 will not only enable manufacturers to meet the proposed requirements 

 with comparative ease, but may indeed enable the limits to be lowered as 

 time goes on. Certain types of vehicles, such as most ordinary cars, are 

 already agreeably quiet, but others, notably motor cycles, have lee-way to 

 catch up ; and the Committee has accordingly suggested breathing space 

 in the shape of periods of grace to meet these and other aspects of the 

 problem of noise as it is on the road to-day. The Committee's task has 

 not been easy, but I trust the limits of noise which it has proposed will, 

 in one way or another, help to ensure a standard of acoustical decency 

 on the roads of this country. 



Following the publication of the Committee's reports, the Minister of 

 Transport received assurance from the manufacturers of motor cycles and 

 sports cars that they will not in future put on the market any new vehicle 

 the noise of which could be regarded as offensive. To assist the motor 

 industry in this laudable object, the Ministry recently set up four noise- 

 testing stations in different parts of the country. At each of these stations 

 an N.P.L. noise meter is installed, and manufacturers are enabled to 

 submit types of their products and so ascertain for themselves how the 

 noise levels compare with the limits proposed. 



The whole question will be further facilitated when the simplified 

 objective noise meter, which has recently been developed by the National 

 Physical Laboratory for the Ministry is put on the market. Such meters, 

 which will be checked against the Laboratory standard meter, should, 

 when available in quantity, be of great assistance at such time as it may 

 be decided to bring into force regulations for dealing with noise on the 

 road. 



As regards the outstanding problem of the abatement of motor-cycle 

 noise, I may mention that the British Cycle & Motor Cycle Manufacturers 

 & Traders Union Ltd., together with the Institution of Automobile 

 Engineers, have recently instituted a programme of research which is to 

 be carried out largely at the National Physical Laboratory. 



(v) Motor horns. — Motor horns, if unduly loud or improperly used, 

 have come to be regarded as a very unnecessary nuisance on the road. 

 In this connection it is generally appreciated that the Ministry of Trans- 

 port's beneficent suppression of horn hooting at night has not only led 

 to no increase in accidents but has taught many people to drive more 



