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Noise-generating aircraft propeller. Aircraft noise is noise pollution produced by an aircraft or its components, whether on the ground while parked such as auxiliary power units, while taxiing, on run-up from propeller and jet exhaust, during takeoff, underneath and lateral to departure and arrival paths, over-flying while en route, or during landing.
A hush kit is an aerodynamic device used to help reduce the noise produced by older aircraft jet engines. These devices are typically installed on older turbojet and low-bypass turbofan engines, as they are much louder than later high-bypass turbofan engines .
The primary sources of jet noise for a high-speed air jet (meaning when the exhaust velocity exceeds about 100 m/s; 360 km/h; 225 mph) are "jet mixing noise" and, for supersonic flow, shock associated noise. Acoustic sources within the "jet pipe" also contribute to the noise, mainly at lower speeds, which include combustion noise, and sounds ...
Noise poses a serious threat to a child's physical and psychological health, and may negatively interfere with a child's learning and behavior. [46] Exposure to persistent noise pollution shows how important maintaining environmental health is in keeping children and elderly healthy. [47]
The FAA Stage 5 noise standards are equivalent. [49] Higher bypass ratio engines produce less noise. The PW1000G is presented as 75% quieter than previous engines. [50] Serrated edges or 'chevrons' on the back of the nacelle reduce noise. [51] A Continuous Descent Approach (CDA) is quieter as less noise is produced while the engines are near ...
Highway noise is today less affected by motor type, since the effects in higher speed are aerodynamic and tire noise related. Other contributions to the reduction of noise at the source are: improved tire tread designs for trucks in the 1970s, better shielding of diesel stacks in the 1980s, and local vehicle regulation of unmuffled vehicles. [13]
In a study conducted by Cornell University in 1993, children exposed to noise in learning environments experienced trouble with word discrimination, as well as various cognitive developmental delays. [50] [51] In particular, the writing learning impairment dysgraphia is commonly associated with environmental stressors in the classroom. [52]
Example of transportation noise and how it affects the community. Environmental noise is an accumulation of noise pollution that occurs outside. This noise can be caused by transport, industrial, and recreational activities. [1] Noise is frequently described as 'unwanted sound'. Within this context, environmental noise is generally present in ...