Code of Federal Regulations (CFR) Title 14 Part 36 – Noise Standards: Aircraft Type and Airworthiness Certification (14 CFR Part 36). The FAA says that a maximum day-night average sound level of 65 dB is incompatible with residential communities. Communities in affected areas may be eligible for mitigation such as soundproofing. Cabin noise Aircraft noise also affects people within the aircraft: crew and passengers. Cabin noise can be studied to address the occupational exposure and the health and safety of pilots and flight attendants. In 1998, 64 commercial airline pilots were surveyed regarding hearing loss and tinnitus. In 1999, the NIOSH conducted several noise surveys and health hazard evaluations, and found noise levels exceeding its recommended exposure limit of 85 A-weighted decibels as an 8-hr TWA. In 2006, the noise levels inside an Airbus A321 during cruise have been reported as approximately 78 dB(A) and during taxi when the aircraft engines are producing minimal thrust, noise levels in the cabin have been recorded at 65 dB(A). In 2008, a study of Swedish airlines cabin crews found average sound levels between 78 and 84 dB(A) with maximum A-weighted exposure of 114 dB but found no major hearing threshold shifts. In 2018, a study of sound levels measured on 200 flights representing six aircraft groups found media noise level of 83.5 db(A) with levels reaching 110 dB(A) on certain flights, but only 4.5% exceeded the NIOSH recommended 8-hr TWA of 85 dB(A). Cognitive effects Simulated aircraft noise at 65 dB(A) has been shown to negatively affect individuals’ memory and recall of auditory information. In one study comparing the effect of aircraft noise to the effect of alcohol on cognitive performance, it was found that simulated aircraft noise at 65 dB(A) had the same effect on individuals’ ability to recall auditory information as being intoxicated with a Blood Alcohol Concentration (BAC) level of at 0.10. A BAC of 0.10 is double the legal limit required to operate a motor vehicle in many developed countries such as Australia. Mitigation programs In the United States, since aviation noise became a public issue in the late 1960s, governments have enacted legislative controls. Aircraft designers, manufacturers, and operators have developed quieter aircraft and better operating procedures. Modern high-bypass turbofan engines, for example, are quieter than the turbojets and low-bypass turbofans of the 1960s. First, FAA Aircraft Certification achieved noise reductions classified as "Stage 3" aircraft; which has