Noise measurement and evaluation

This review outlines the history of noise measurement in the `pre-electronic¿ era, and then goes on to describe current practice. The first five Sections are devoted to the `engineering¿ aspects of the subject, i.e. the methods used to make physical measurements of noise parameters viewed as a series of pressure fluctuations in the air. As well as measurements at normal levels in the normal audio-frequency range, special techniques for unusually high and low frequencies and pressure levels are described, together with integrating techniques to determine the total sound output from sources. The second half of the review is devoted to techniques of noise evaluation. This subject, which is currently an area of more activity than the physical measurement side, deals with the relationship between the measurable physical parameters of the noise and its effects on the human organism. These effects include annoyance, discomfort, interference with communication, and damage to hearing. They are due not only to noise in the audible-frequency range, but also to low-frequency and infrasonic noise. Those areas are indicated where present knowledge is limited and further research and standardisation are required.