The sensitivity of the human ear to sound depends on the sound frequency and its intensity, which in turn are related to the distance from the source. On the other side of the eardrum (middle and inner ear), the cochlear organ converts the sound signal into electrical impulses that are sent to the brain. Briefly, sound waves enter our ear canal (outer ear) and travel through our eardrum. Noise is felt by our hearing system and converted into electrical impulses that travel to our brain where they are processed. These and many other complex sound phenomena are studied in detail in the advanced environmental physics field of acoustics ( Liu et al., 1997 and Boeker and van Grondelle, 1999). The remainder of the sound wave is likely to be distorted and much lower in intensity. For example, a sound wave may pass through a window, transferring some of its energy into the glass in the form of mechanical energy. Saunders Company, Philadelphia.Īir sound can be transmitted, reflected, absorbed, and distorted by solid objects. Physical Science with Environmental and Other Practical Applications. Widespread complaints Occasional complaintsįrom Turk, J., Turk, A., 1977. For example, sound travels about 346 m s –1 through air, and about 4.2 and 14.8 times faster through water and iron metal, respectively.Įffects (as Ranges About Each Designation Listed) All media, including air, liquids, and solids, transmit sound waves, but the speed of sound movement varies dramatically through each medium. The vibrations of audible sounds range from about 16 to 20,000 Hz (oscillations per second). Sound is energy in the form of airborne vibrations or pressure waves that can be sensed or heard through our hearing system. Noise is an insidious form of pollution that is increasing in modern day life. This section presents a short summary of the physics of noise, followed by a discussion of the sources of activities that produce noise and the increasing impacts of noise on modern life. Existing local noise ordinances vary widely and often they are disregarded or poorly enforced. Thus there are no explicit national, state, or local laws that protect the public against noise pollution. In addition, EPA does not have the funding to enforce or revise these regulations. However, to date the EPA has set only transportation-related noise regulations. Since the 1970s the Occupational Safety and Health Administration (OSHA) has implemented standards for noise exposure in the workplace for worker protection. In 1990 an amendment to the Clean Air Act EPA added title IV, which deals with noise abatement. EPA powers to set noise emission standards for major transportation and industrial sources of noise, to protect public health and welfare. In the United States, the Noise Control Act of 1972 gave the U.S. Loud noises can also place people and animals in danger, because they may prevent the hearing of potential or impending dangers. If noise is loud enough and continuous, it can produce temporary and even permanent damage to our hearing system. Noise is defined as unwanted or unwelcome sound that produces annoyance or physiological stress. Brusseau, in Environmental and Pollution Science (Third Edition), 2019 18.4 Noise Pollution
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