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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.
Acoustic sources within the "jet pipe" also contribute to the noise, mainly at lower speeds, which include combustion noise, and sounds produced by interactions of a turbulent stream with fans, compressors, and turbine systems. [1] The jet mixing sound is created by the turbulent mixing of a jet with the ambient fluid, in most cases, air.
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 ...
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 agency's goal was to reduce the number of people around airports exposed to a day-night average aircraft sound level of 65 decibels to less than 300,000 by 2018. [192] One way the agency planned to achieve it was by adopting a new noise standard for certain newly certificated subsonic jet airplanes and subsonic transport category large ...
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.
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]
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]