![]() The six groups of 200 aircraft of 23 different aircraft models for the study were mainly narrow-body aircrafts such as B737, B757, A320, MD80, MD88, MD 90, and a few wide-body aircrafts such as B767. The mean sound levels across all flight phases and aircraft groups were found to range from 37.6 dB(A) to greater than 110 dB(A), with a median value of 83.5 dB(A). measured the sound levels on 200 flights, representing six aircraft groups using continuous monitors. , based on a study of Swedish airlines cabin crews, found average sound levels between 78–84 dB(A) with maximum A-weighted exposure of 114 dB(A) but found no major hearing threshold shifts. Discontinuous in-cabin noise levels were observed to reach levels as high as 81–88 dB(A). For their in-flight measurement of two Airbus A321 commercial planes, which were also narrow-body aircraft, the continuous noise levels were 60–65 dB(A) before takeoff, 80–85 dB(A), and 75–80 dB(A) during flight and landing, respectively. ![]() Ozcan and Nemlioglu classified the interior noise or cabin noise into continuous types caused by aircraft engines or motion and discontinuous types due to human activities or announcements in the plane. The 8-h total weight average (TWA) is the permissible exposure limit (PEL) defined by the US Occupational Safety and Health Administration. Several noise surveys conducted by the NIOSH in 1999 found noise levels exceeding its recommended exposure limit of 85 dB(A) as an 8-h TWA. , based on a survey of 64 commercial airline pilots, reported that within specific age groups, the proportions responding positively regarding hearing loss and tinnitus exceeded the corresponding proportions in the general population reported by the National Center for Health Statistics. There is a potential risk of excessive noise exposure on crew and passengers, especially for long-haul flights. Thus, aircraft cabin noise assessment is essential for passengers and flight crew’s health, comfort, and psychological wellness, especially for long-haul flights. The noise is usually higher for older airplanes or towards the back of a plane. Besides the cockpit noise, all the other primary and secondary noise sources contribute to the cabin noise experienced by the passengers. The secondary sources of aircraft noise are other aircraft systems such as landing gears, extension of flaps and slats, cockpit noise, cabin noise due to passenger conversion, public address system, toilet flushing noise, and noise caused by passenger services. The primary sources of aircraft noise are airflow noise engines and air-conditioning systems. At cruising altitudes, noise could drop to below 85 dB(A). ![]() Fortunately, these two flight events are typical of concise duration. The take-off and landing operations were the loudest moments, with a potential maximum level of 105 dB(A). In a BBC report in 2014, it was reported that the noise experienced in the interior or cabin of an aircraft during a typical plane journey could vary significantly. The flight duration from Singapore to Europe is about 11 to 13 h. Moreover, the typical flight durations between cities in Asia are about one to seven hours. The longest commercial flight is the Singapore Airlines Flight between Singapore Changi Airport and New York Newark Airport, covering 15,344 km using an Airbus A350-900ULR aircraft with nearly 19-h flight duration. ![]() A short-haul route is shorter than 1500 km, whereas a long-haul route is longer than 4000 km. Commercial flights are often categorized into long, medium, or short-haul by commercial airlines based on flight length. The aviation industry has seen dramatic growth over the past many years till the recent disruption due to the COVID-19 pandemic, with passenger numbers rising from 1.467 billion in 1998 to 4.5 billion in 2019, based on the reported statistics from the International Civil Aviation Organization.
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