The National Aeronautics and Space Administration (NASA), Langley Research Center (LaRC) and the Environmental Measurement and Modeling Division of the United States Department of Transportation's John A. Volpe National Transportation Systems Center (Volpe) conducted a noise measurement study to examine the sound level directivity pattern behind aircraft start-of-takeoff roll. This report discusses the procedures and methodologies used to measure and quantify data acquired from the Study.

Sounds associated with oversnow vehicles, such as snowmobiles and snowcoaches, are an important management concern at Yellowstone and Grand Teton National Parks. The John A. Volpe National Transportation Systems Center's Environmental Measurement and Modeling Division is supporting the National Park Service with its on-going Winter Use Planning program. As part of this support, acoustic measurements of ten snowcoaches and six snowmobiles were made at the south entrance to Yellowstone National Park from the 26th through the 28th of February 2008. Measurement methodologies were guided by SAE J1161 and SAE J192. There were two primary objectives: 1) to determine which snowcoaches had the Best Available Technology (BAT) with respect to noise emissions, and 2) to determine if there was a significant difference between snowmobile sound levels when tested using two revisions of SAE J192.

This study provides new insights into aircraft plume behavior that greatly surpasses historic understanding, and data for more accurate modeling of plume rise and spread from commercial aircraft at airports. This final report completes individual analysis of the LAX data set, initially reported in the related Preliminary Report published in September 2002. Additional studies are planned (based on available funding) to analyze potential changes in the derived parameters due to site characteristics (e.g., elevation, weather conditions) and will be reported on as the work continues.

In March 1998, the Federal Highway Administration (FHWA) Office of Natural Environment, released the FHWA Traffic Noise Model (FHWA TNM) Version 1.0, a state-of-the-art computer program for highway traffic noise prediction and analysis. Since then, the FHWA, with assistance from the Volpe Center Acoustics Facility (Volpe Center) and Foliage Software Systems (FSS), have released updates of TNM (Versions 1.0a, and 1.0b) in March 1999 and August 1999, respectively. In support of the FHWA and the California Department of Transportation, the Volpe Center and FSS released Version 1.1 in September 2000. TNM 2.0 is the latest release of the TNM software. Two companion reports were released with TNM Version 1.0, a Technical Manual that describes the acoustics within TNM and a User's Guide. In addition, prior to TNM release, a data report was published that describes the vehicle noise-emissions data base within TNM. This document is an addendum to the FHWA TNM Version 1.0 User's Guide. It details the enhancements in the program up to and including Version 2.0.

Two procedures for adjusting as-measured test-day spectra to reference day conditions - the Society of Automotive Engineers' (SAE) Aerospace Recommended Practice (ARP) No. 866A (866A) and a procedure utilizing pure-tone absorption equations, developed in support of the International Organization for Standardization's (ISO) 9613-1 and the American National Standards Institute's (ANSI) S1.26-1995, and refined for application to one-third octave-band data- were evaluated and compared. The ISO and ANSI pure-tone absorption equations are identical to each other. The 866A procedure historically has been used for atmospheric absorption corrections for Federal Aviation Regulations (FAR) Part 36, Noise Standards: Aircraft Type and Airworthiness Certification and similar regulations of the International Civil Aviation Organization (ICAO). The ISO/ANSI procedure analyzed herein is under consideration for inclusion into harmonized regulations. This document presents a comparison of data corrected to several distances using the two different methodologies.