Noise mitigation programs are strictly regulated under 14 CFR Part 150 (Part 150 Study), which mandates use of federally-established aircraft noise exposure calculations and thresholds for defining eligibility. The process for calculating aircraft noise exposure includes using the Integrated Noise Model (INM) and inputting numerous pieces of aircraft operations data that specifically include a 10-decibel (dB) penalty for each aircraft operation occurring between 10 p.m. and 7 a.m. This penalty is intended to account for the higher human sensitivity to noise during the nighttime hours. The calculations result in noise contours that depict areas impacted by cumulative aircraft noise exposure levels of 60, 65, 70 and 75 dB DNL. The Federal Aviation Administration specifies that only residences impacted by cumulative aircraft noise exposure level of 65 dB DNL or greater are considered incompatible with an airport and thus eligible for sound insulation programs using aviation-generated revenues. Homes that fall outside these levels are ineligible for sound insulation.