A recent term used to suggest the destructive effects of excessive sound, usually based on properties of loudness and irritation. Some adverse effects of NOISE may be physiological (see BOILERMAKER'S DISEASE, HEARING LOSS, THRESHOLD SHIFT), others psychological (anxiety, nervousness, loss of sleep, etc.) and still others communicational (see JET PAUSE, SPEECH INTERFERENCE LEVEL). Since physiological damage has been well researched, remedies are better known and are beginning to be adopted, for instance, in DAMAGE-RISK CRITERIA for industrial noise. See: OCCUPATIONAL DEAFNESS.
Although there is evidence that exposure to certain modern environmental sounds may pose a hearing risk (see PRESBYCUSIS, SOCIOCUSIS), it has been more difficult to set limits on environmental sounds, though many countries and cities have attempted to do so, particularly for technological noises such as automobiles, air conditioners, etc. Composite zoning along acoustic lines is employed in Japan, Switzerland, parts of Australia and in Scandinavia. In this case, the general AMBIENT NOISE LEVEL is monitored in order to ensure that the level does not exceed set limits more than 10% of the time. In other parts of Europe and North America, limits are set for particular noisy sounds and these are checked wherever they may occur.
The problem of noise pollution is complex and it is difficult as yet to know whether noise pollution in the community is being brought under effective control. Comparisons between recent surveys suggest that the ambient noise level of cities is continuing to rise, perhaps by as much as 0.5 dB per year.
For various noise measurement systems, see COMMUNITY NOISE EQUIVALENT LEVEL, COMPOSITE NOISE RATING, EQUIVALENT ENERGY LEVEL, NOISE AND NUMBER INDEX, NOISE EXPOSURE FORECAST, NOISE CRITERION, NOISE LEVEL, NOISE POLLUTION LEVEL, NOISE RATING, PERCEIVED NOISE LEVEL, TRAFFIC NOISE INDEX. See also: DECIBEL, SOUND LEVEL, SOUND LEVEL METER, SOUND PRESSURE LEVEL, WORLD SOUNDSCAPE PROJECT.
The psychosocial effects of noise pollution have scarcely been considered in noise abatement legislation, mainly because they are less easily quantifiable. However, such effects should not be neglected, and noise pollution will not be under control until they too have been significantly reduced.
For a contrasting attitude towards the problem in terms of the SOUNDSCAPE, see SOUND INTRUSION, SOUND POLLUTION. Compare: silence.
In the absence of a SIGNAL, the NOISE which comprises all interference, including HUM and HISS, in a system which stores, reproduces or measures sound. Its level is measured by the SIGNAL-TO-NOISE RATIO. The term is also used colloquially to denote AMBIENCE.
See: COMPRESSION, DUBBING, DYNAMIC RANGE, gaussian noise, random noise, rustle noise, white noise. Compare: KEYNOTE SOUND, LO-FI, silence.
Stop right where you are and listen. What do you hear? You might hear the fan of your computer, a hum from the monitor, a car pass by, machines across the street, a child, or water running. What kinds of sound to you hear at work. Co-workers, printers, copiers, vehicles, machinery, the effects of wind? All of these things create noise. Machines may make our life easier but they can create a lot of noise. Exposure to constant frequencies of noise can cause hearing loss. It is important to know about the noise around you, how to control it, and how you might take precautions to avoid damage to your own hearing.
In this module you will learn about environmental noise, it's effects on people, how to control it, and instruments that can be used to measure noise.
Noise in the environment is receiving more and more attention. Do you remember what it sounds like when you are up in the mountains, or out by yourself in the wilderness or park? Is it quiet? Probably not absolutely quiet, but compared to the noise in your city, or neighbourhood, it is quiet. As we use modern technology and machines to make our life easier, we create noise.
In this chapter we will take a look at different sources of noise in the environment and how it is created. As you read this chapter, you may wish to think of innovative ways to reduce the noise generated my machines and other devices.
Noise in the environment is receiving more and more attention. Do you remember what it sounds like when you are up in the mountains, or out by yourself in the wilderness or park? Is it quiet? Probably not absolutely quiet, but compared to the noise in your city, or neighborhood, it is quiet. As we use modern technology and machines to make our life easier, we create noise.
In this chapter we will take a look at different sources of noise in the environment and how it is created. As you read this chapter, you may wish to think of innovative ways to reduce the noise generated my machines and other devices.
Accelerometer
Aerodynamic noise
Day-light level Ldn
Dipole source
Equivalent level Leq
Monopole source
Quadrupole source
Refraction
In the third module you learned about the complex process of hearing. In the web activity you read an article about how loud music can cause temporary or permanent hearing loss. In this chapter we will look at ways that noise can cause hearing loss, and mental health problems in people.
Noise affects people in many ways. In addition to hearing loss, noise interferes with speech commiunications, sleep, and work. In this chapter we will look at ways noise can cause temporary or permanent hearing loss, and other physiological and psychological effects of noise in people.
Articulation index
Audiogram
Audiometer
Electroencephalogram
Canyoupronouncethatone
Equal energy hypothesis
Equal temporary effects (TTS) hypothesis
Hair cells
Permanent threshold shift (NIPTS)
Presbycusis
Rapid eye movement (REM) state
Speech cues
Speech interference level (SIL)
Temporary threshold shifts (TTS)
Now that you understand the effects of noise in our environment and on people, it is time to learn about how you can control it. This ranges from laws and regulations, to sound absorption panels, piles of dirt, high walls, and the application of different types of acoustical materials.
Aerodynamic
Critical frequency
FAR Part 36
Fresnel number
IIC (impact isolation class)
Infrasonic
OSHA (Occupational Safety and Health Agency)
Sonic boom
STC (sound transmission class)
Supersonic
TL (transmission loss)
Turbofan engine
Ultrasonic
Waveguid