Integrated Noise Model (INM) Version 7.0 Technical Manual

The Federal Aviation Administration, Office of Environment and Energy (FAA, AEE-100) has developed Version 7.0 of the Integrated Noise Model (INM) with support from the John A. Volpe National Transportation Systems Center, Acoustics Facility (Volpe Center) for development of the acoustic computation module, and from the ATAC Corporation for systems integration, development of the graphical interface, and methods for computing aircraft flight profiles and constructing flight paths, which are processed by the acoustics module. This Technical Manual describes the core technical components in INM Version 7.0, including the flight-path methodology (Chapter 2), along with the basic methodology employed by the INM to compute noise levels or time-based metrics at a single, user-specified observer, or at an evenly-spaced, regular grid of observers (Chapter 3). The noise/time computation methodology includes a description of: (1) computation of the flight-segment geometric and physical parameters; (2) flight-segment noise-level interpolation process; (3) atmospheric absorption adjustment; (4) acoustic impedance adjustment; (5) flight-segment noise-fraction adjustment for exposure-based metrics; (6) aircraft speed adjustment for exposure-based metrics; (7) updated lateral attenuation adjustment; (8) ground-based directivity adjustment for observers behind start-of-takeoff-roll, as well as for computing metrics associated with run-up operations; (9) new helicopter noise modeling capabilities and associated adjustments (including advancing tip mach number, lateral directivity, static directivity and static duration adjustments); (10) metric computation process; and (11) development of a recursively-subdivided irregular grid methodology, which is used for computing noise contours (Chapter 4).