An active space is a well-known sensory concept from bioacoustics (Marten and Marler 1977, Gabriele et al. 2018). It represents a geographic volume whose radii correspond to the limit of audibility for a specific signal in each direction. In other words, an active space provides an answer to the question, "how far can you hear a certain sound source from a specific location on the Earth's surface?"

This repository is designed to estimate active spaces for motorized noise sources transiting the U.S. National Park System. Aircraft are powerful noise sources audible over vast areas. Thus considerable NPS management efforts have focused on protecting natural quietude from aviation noise intrusions. For coastal parks, vessels are similarly powerful noise sources of concern. For both transportation modalities NPS-ActiveSpace provides meaningful, quantitative spatial guides for noise mitigation and subsequent monitoring.

Consider an example active space, below. It was computed using data from a long term acoustic monitoring site in Denali National Park, DENAUWBT Upper West Branch Toklat (Withers 2012). The bold black polygon delineates an active space estimate for flights at 3000 meters altitude. Points interior to the polygon are predicted to be audible, those exterior, inaudible.

Superposed over the polygon are colored flight track polylines. NPS-ActiveSpace includes an application that leverages the acoustic record to ground-truth audibility of co-variate vehicle tracks from GPS databases. Ground-truthing is used to "tune" an active space to the appropriate geographic extent via mathematical optimization.

This project is made up of four packages:

utils: diverse utilities - file I/O, geoprocessing computations, acoustic propagation modelling, and detection statistics

ground-truthing: a tkinter-based ground-truthing application

active-space: generate and optimize active space polygons

analysis: estimate acoustic metrics from the intersection of an active space polygon and vehicle tracks (currently in development, see Analysis branch)

Also included are noise source data for tuning active space polygons.

For more specific information on each package, view their individual READMEs.

While each package can be used and run individually, the project was designed so that outputs of one package work seamlessly as the inputs for another.

Packages were designed to be run in the following order:

ground-truthing $\rightarrow$ active-space $\rightarrow$ analysis

This project is in the worldwide public domain:

This project is in the public domain within the United States, and copyright and related rights in the work worldwide are waived through the CC0 1.0 Universal public domain dedication.

All contributions to this project will be released under the CC0 dedication. By submitting a pull request, you are agreeing to comply with this waiver of copyright interest.

Publications about NPS-ActiveSpace:

Betchkal, D.H., J.A. Beeco, S.J. Anderson, B.A. Peterson, and D. Joyce. 2023. Using Aircraft Tracking Data to Estimate the Geographic Scope of Noise Impacts from Low-Level Overflights Above Parks and Protected Areas. Journal of Environmental Management 348(15): 119201 https://doi.org/10.1016/j.jenvman.2023.119201