NOISE MEASUREMENT SYSTEMS


Simple measurements of sound magnitude cannot deal with all of the environmental and communicational factors encountered in noise problems wherever they occur. Specialized measurement and evaluation systems have had to be developed which take a variety of additional factors into account, such as the frequency content and time-dependence of the noise, interference with speech communication, criteria for indoor environments intended for certain activities, evaluation of specific noise sources such as traffic and aircraft, establishing overall community noise impact, and so on.

In most cases, the pattern is to quantify the noise and correlate it to individual or community reaction, usually with the aim of establishing "acceptable" or "recommended" levels, or in some cases, in order to predict the impact of higher noise levels. The criteria arrived at are often used by various levels of government in establishing by-laws, standards and guidelines for noise control and abatement.

The specific case of damage-risk criteria for hearing protection in industry is considered under the larger topic of Audiology and Hearing Loss. Other noise measurement systems are presented here under the following general headings:

A) Basic measurement systems: a review of common "level" measurements;
Decibel
Sound Pressure Level
Sound Level
Sound Level Meter
Noise Level
Ambient Noise Level
Equivalent Energy Level
Perceived Noise Level

B) Speech communication criteria;
Speech Communication Criterion
Articulation Index
Speech Interference Level

C) Indoor environment criteria;
Preferred Noise Criterion
Noise Criterion
Noise Rating

D) Aircraft and Traffic measurement systems and their correlation to public annoyance;
Noise and Number Index
Noise Exposure Forecast
Composite Noise Rating
Effective Perceived Noise Level
Traffic Noise Index

E) Community noise evaluation systems;
Noise Pollution Level
Community Noise Equivalent Level

F) Measurement of absorption, reflection and transmission properties of materials as criteria for sound insulation.
Absorption
Absorption Coefficient
Reflection Coefficient
Impact Insulation Class
Sound Transmission Class
Sound Insulation
Noise Reduction Factor
Noise Reduction Coefficient
Noise Isolation Class
Sound Transmission Coefficient

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