Effects of Noise pollution
The extent of the noise problem is large. In the EU countries about 40 % of the population are exposed to road traffic noise with an LAeq,T exceeding 55 dB daytime and 20 % are exposed to levels exceeding 65 dB (Lambert & Vallet, 1994). Taking all exposure to transportation noise together about half of the EU citizens are estimated to live in zones which do not ensure acoustic comfort to residents. More than 30 % are exposed at night to noise levels exceeding 55 dB LAeq which are disturbing to sleep. It is no surprise that annoyance to community noise is widespread among citizens: in some EU-countries 20-25 % are being annoyed by road traffic, 2-15 % by aircraft, and 2-4 % by railway noise (Lambert & Vallet, 1994).
Until now the introduction of noise emission standards for vehicles have had limited impact on the exposure to road traffic noise (Sandberg, 1993). Traffic planning and correction policies may diminish the number of people exposed to the very high community noise levels (>70 dB LAeq) but the number exposed to moderately high levels (55-65 dB LAeq) continues to increase in industrialized countries.
A substantial growth in air transport in Europe is expected in the future; in the U.K. by 50-80 % in passenger movements over ten years. General aviation noise at regional airports will increase (Large & House, 1989). However, at the same time jet aircrafts may become 8 to 12 dB quieter due to regulation. An outlook for exposure to noise has been made by OECD (1991). The number of noise sources is expected to increase and is likely to be accompanied by a deterioration of the noise environment. At the same time, it is expected that the public will become more aware of noise pollution and also be protected from noise problem. The OECD (1991) identifies the following four factors of increasing importance in the future: (1) Expanding use of increasingly numerous and powerful sources of noise.
(2) Wider geographical dispersion of noise sources together with greater individual mobility and spread of leisure activities.
(3) Increasing spread of noise over time particularly in the early morning, evenings and weekends.
(4) Increasing public expectations which are closely linked to increases in incomes and in education levels.
The OECD (1991) report forecasts (a) a strengthening of present noise abatement policies and their applications, (b) a further sharpening of emission standards, (c) a coordination of noise abatement measures and transport planning, particularly designed to reduce mobility, and (d) a coordination of noise abatement measures with urban planning.
High-level noise exposures giving rise to noise-induced hearing deficits are by no means restricted to occupational situations. Such levels can also occur in concerts, discotheques, motor sports, shooting ranges, and leisure activities. Other sources are also important such as music played back in headphones and impulse noise from toys and fireworks. It has also been argued that community noise exposure would be a contributing factor to hearing deficits with increasing age. The existence of such a ˇ§sociacusisˇ¨ waits for final scientific verification since so many other factors and agents are also influencing hearing.
The acoustics of a space designed for speech must primarily ensure clarity and intelligibility. Therefore it is important to design spaces for optimum reverberation time and spatial-temporal aspects including the time delay between the direct and first reflected sound.
Planners need to know the likely effects on the noise pollution in a community of introducing a new noise source as well as increasing the level of an existing source (Diamond & Rice, 1987). There are a number of models to predict annoyance due to a combination of noise sources, such as models of energy summation, of source addition, of source difference, of response summation and response inhibition, and of the (subjectively) dominant source (e.g., Vos, 1992a). Policy makers, when considering applications for new developments, must take into account maximum levels, equivalent levels, frequency of occurrence, and operating time of the major noise sources.
Noise Threatens Hearing
Noise is one of the leading causes of hearing loss in the 28 million people with impaired hearing in the United States, and health statistics suggest a trend that the incidence of hearing loss is occurring at younger and younger ages. Noise-induced hearing loss, though preventable, is permanent.
How Loud is Too Loud?
To know if a sound is loud enough to cause damage to your ears, it is important to know both the level of intensity and the length of exposure to the sound. The unit used to measure environmental sound intensity is the decibel (dBA).
Zero decibels is approximately the softest sound the healthy human ear can hear. The scale increases logarithmically; that is, the level of perceived loudness doubles every 10 decibels. Experts agree that continued exposure to noise above 85 dBA, over time, will eventually harm hearing. In general, the louder the sound, the less time required before hearing will be affected.
Noise-Induced Hearing Loss - How
the Damage Occurs
Loud noise assaults the delicate hair cells of the inner ear. Noise-induced hearing loss typically occurs gradually and without pain. After exposure to loud noise, a person may experience ringing in the ears or difficulty hearing. This is called a "temporary threshold shift". After a few hours (or in some cases, a few days), this temporary shift in hearing returns to normal. With repeated exposure, however, this temporary shift in hearing can become permanent. Once permanent hearing damage has occurred, it is not possible to restore hearing.
Pay Attention to the Warning
Noise-induced hearing loss is cumulative across the life span. Often, by the time a person realizes that there is hearing loss, it is too late. But there are certain early warning signs to suggest that there may be a problem. If you experience any of the following early warning signs, have your hearing tested by a licensed audiologist, or have your ears examined by an ear doctor.
A ringing or buzzing (tinnitus) in the ears immediately after exposure to noise.
A slight muffling of sounds after exposure making it difficult to understand people when you leave a noisy area.
Difficulty understanding speech; that is, you can hear all the words, but you can't understand all of them.
Protect Your Hearing
To avoid noise-induced hearing loss, pay attention to the noises around you and turn down the volume whenever possible. Avoid or limit time spent in noisy sports events, rock concerts and night clubs. Wear adequate hearing protection, such as foam ear plugs or ear muffs, when you must be in a noisy environment or when using loud equipment.