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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Advanced Acoustic Modeling of Urban Air Mobility Concept Vehicles

Wednesday, April 20, 2022

The U.S. transportation network will look dramatically different in the coming years as advanced air mobility vehicles are introduced that will change the way people travel within and between metropolitan areas. To prepare for this innovative future, transportation experts are researching the potential noise impacts of these vehicles on communities and urban populations.

In spring 2020, NASA transferred the Advanced Acoustic Model (AAM) to the U.S. DOT Volpe Center to improve and expand the modeling tool. AAM software allows users to model vehicle sound generated by helicopters, tiltrotor vehicles, and fixed-wing aircraft using site-specific receivers. In partnership with NASA, U.S. DOT Volpe experts conducted an acoustic analysis of a NASA Urban Air Mobility (UAM) concept vehicle to demonstrate modeling tool interoperability. U.S. DOT Volpe Center staff conducted a comparative analysis with other existing tools and demonstrated the importance that source noise directivity and propagation modeling fidelity have on predicted results. The U.S. DOT Volpe Center hopes to expand the use of AAM and increase its customer base to other areas, including the future UAM arena.

A sound acoustic model map that allows planners to visualize the noise in the community
A screenshot from an acoustic animation that allows the vehicle designer and operations planner to “see” the noise being emitted into the community. The tool allows designers to take into account local time and varying background noise levels to assess loudness metrics at particular points of interest and understand the specific acoustic spectral emission directivity. (U.S. DOT Volpe Center graphic)

Since AAM version 3.0’s release in December 2020, the suite of software tools has been provided to more than 75 entities and individuals worldwide, representing the aerospace and transportation industry, the U.S., and international government agencies and academic institutions. AAM provides a high-fidelity mechanism for air vehicle designers to project community sounds; assess impacts of future vertiport and skyport plans; and for researchers to evaluate advanced metrics beyond those currently supporting regulatory or National Environmental Policy Act (NEPA) actions.

U.S. DOT Volpe Center released beta versions of the AAM software version 3.1 in May and July 2021 and beta version 3.2 in April 2022. These beta versions offer additional enhancements to analyze higher fidelity noise defined in terms of narrow band acoustics from UAM vehicles. The Air Force Civil Engineering Center in San Antonio, Texas supports distribution of AAM software via the U.S. DOT Volpe Center website, as it is an integral part of the noise analysis of military aircraft for NEPA. A paper titled “Comparison of Two Community Noise Models Applied to a NASA Urban Air Mobility Concept Vehicle” was published jointly by NASA and the U.S. DOT Volpe Center at Inter-Noise in August 2021, which assessed modeling applicability, capabilities, and limitations. The paper also identified potential future modeling improvements.

The U.S. DOT Volpe team completed the bulk of this innovative project in 2021, but additional sponsor funding will allow for continued analysis and AAM model development for UAM.

*This story appeared in the U.S. DOT Volpe Center’s January 2022 publication: The U.S. DOT Volpe Center’s 2021 Annual Project Accomplishments.

Celebrating more than 50 years of federal service to the nation, the U.S. DOT Volpe Center’s mission is to transform transportation for all.