physical-propagation 0.6.1

A collection of code to determine how the acoustic levels propagating through the air will be altered

Physical Propagation

For simplistic geometric acoustics we can use the information regarding the atmosphere and ground to determine nominal acoustic losses that a spherical wave would experience as the signal moves through the atmosphere. This code originated in the calculation of equivalent sources that were created as part of the Acoustic Repropagation Technique ART that was developed as part of the Rotorcraft Noise Model. The same de-propagation methods were employed by the Swiss Federal Laboratories when they created a series of sources using spherical harmonics.

The author of this package took these elements, originating with a variety of ANSI standards and Acoustical Society of America papers, and created a series of C++, Matlab, and C# codes to determine the nominal losses. These culminated in the author's dissertation regarding the de-propagation of measurements on a UH-1J (Huey).

This package contains acoustic losses for:

• Spherical spreading (divergence) of spherical waves
• Atmospheric absorption
• Ground reflection

An additional code is available to trace the acoustic ray through a media defined by a series of horizontal and vertical temperature & wind speed gradients.

This code is part of a series of packages that were developed from the C# codes for the purpose of providing a code base for continued creation of acoustic propagation and perception.

This code requires PythonCoordinates, a package with measurable objects to assist in the calculation of the physical losses and the location within the world and relative coordinates of the various objects.

Physical Acoustic Propagation

2023

April

• Initial creation of the package and establishment of the repository on ELSZ.

July

• Began the process of updating the package to be converted to a public repository. Public Affairs clearance will be required prior to posting.
• Received public affairs clearance to put this code on Pypi.org

MIT License

Copyright (c) 2021 Frank Mobley, Gregory Bowers

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

This software was cleared for public release with case number AFRL-2023-3282 on 10 July 2023. This clearance is value until 10 July 2026.