A.— MATHEMATICAL AND PHYSICAL SCIENCES 31 



is not crying for the moon. The most he needs ask of a particular locality 

 is that its background of noise, whether by day or night, shall be suited 

 to the environment and the reasonable habits of a majority of its occupants. 



In this matter of noise abatement, the British Association has played a 

 leading part, through the intermediary of both this Section and the 

 Engineering Section which set up a Noise Committee in 1933. The 

 subject has since become one of international concern, as is evidenced by 

 the formation of a League of Nations Commission which held its first 

 meeting at Geneva in June this year, and over which I had the honour 

 to preside. 



On the question of what constitutes a noise, it is difficult to generalise. 

 The countryman votes the noises of the city as disturbing to a degree, 

 nor does the townsman necessarily find a lullaby in the noises peculiar 

 to the countryside. Many offending noises owe their origin to ill-timed 

 activities or pure thoughtlessness. The young person hearing the 

 raucous horn with which a friend announces his arrival has no doubt as 

 to its character : neither has the invalid next door. A hearer is in fact 

 patently influenced by psychological and other factors such as back- 

 ground, environment or force of association. There are those, moreover, 

 who have no hesitation in regarding any sound made by some one else 

 as an objectionable noise, while in contrast there are others who seem 

 quite immune to noise and incidentally behave as if they find silence 

 intolerable. Healthy children obviously revel in noise, at any rate of 

 their own making, and the observation appears to apply to many of a 

 larger grovvth who are in exuberant health, not excluding the Latin races. 



The prejudicial effects of certain extremely noisy occupations on the 

 hearing are recognised, but it would appear that the noises encountered in 

 ordinary everyday life are unlikely to impair the hearing, though there 

 is some evidence that in certain types of work they may adversely affect 

 human efficiency. Most mental workers and particularly mathematicians 

 would agree, I think, that noise is an impossible environment to work in. 

 But while many forthright statements have been made about the effects 

 of noise — and no one would withhold sympathy from those unfortunates 

 whose sleep is regularly violated by noise — the root of the matter is 

 probably that for a good many people noise aggravates rather than 

 initiates psychological distress, being a sort of ' last straw ' for the sick, 

 the fatigued, or the highly strung. The emotionally stable, on the other 

 hand, have clearly a considerable power of accommodation and can get 

 so used to certain classes of noise as never to notice them, though, were 

 the noises arrested, they would not only quickly miss them but might 

 even, on occasion, confess to an unexpected feeling of relief. 



Without doubt then, while there are noises in the world so inappropriate 

 or outrageous as to raise protest alike from the average hearer, the relatively 

 immune, or the hypersensitive, there are equally many border-line sounds 

 on which we should expect them to express very different opinions. 

 In some recent annoyance tests on motor horns at the National Physical 

 Laboratory, in which some two or three hundred observers were employed, 

 it was interesting to note the divergency of views under like conditions of 

 hearing. There was, it is true, a considerable consensus of opinion in 



