; (2) the airport operator’s request would not, in the judgment of the Administrator, conflict with the safe and efficient operation of the national airspace system; and (3) the effect of a modified departure procedure would not significantly increase noise over noise sensitive areas, as determined by the Administrator. 157. Study on potential health and economic impacts of overflight noise (a) In general Not later than 180 days after the date of enactment of this Act, the Administrator of the Federal Aviation Administration shall enter into an agreement with an eligible institution of higher education to conduct a study on the health impacts of noise from aircraft flights on residents exposed to a range of noise levels from such flights. (b) Scope of study The study shall— (1) include an examination of the incremental health impacts attributable to noise exposure that result from aircraft flights, including sleep disturbance and elevated blood pressure; (2) be focused on residents in the metropolitan area of— (A) Boston; (B) Chicago; (C) the District of Columbia; (D) New York; (E) the Northern California Metroplex; (F) Phoenix; (G) the Southern California Metroplex; (H) Seattle; or (I) such other area as may be identified by the Administrator; (3) consider, in particular, the incremental health impacts on residents living partly or wholly underneath flight paths most frequently used by aircraft flying at an altitude lower than 10,000 feet, including during takeoff or landing; (4) include an assessment of the relationship between a perceived increase in aircraft noise, including as a result of a change in flight paths that increases the visibility of aircraft from a certain location, and an actual increase in aircraft noise, particularly in areas with high or variable levels of nonaircraft-related ambient noise