Read the passage and answer the following questions:
As more people live closer together, and as they use machines to produce leisure, they find that their leisure, and even their working hours, become spoilt by a by-product of their machines -- namely, noise. Noise is nowadays in the news; it has acquired political status, and public opinion is demanding, more and more insistently, that something is done about it. To control noise is to demand much self-discipline (annoyance arises often from lack of common courtesy), a sense of proportion (there is usually a conflict of interest if a noise is to be stopped), the expenditure of money (and it is far more economical to do this early rather than late), and finally, technical knowledge.
Technical difficulties often arise from the subjective-objective nature of the problem. You can define the excessive speed of a motorcar in terms of a pointer reading on a speedometer. But can you define excessive noise in the same way?
You find that with any existing simple "noisy-meter", vehicles, which are judged to be equally noisy, may show a considerable difference on the meter.
Though the ideal cure for noise is to stop it at its source, this may in many cases be impossible. The next remedy is to absorb it on its way to the ear. Domestic noises may perhaps be controlled by forethought and industrial noises by good planning and technical improvement. But if we are going to allow fast motorcycles and heavy lorries to pass continuously through residential and business districts, the community must decide on the control it needs to exercise, for, in the long run, it has got to pay for it. And if a nation is to take part in modern air transport, it must enter into international agreements on the noise control measures it will impose on its airports -- and here the cost of any real control is to be measured in millions of dollars.