USING NOISE MODEL SIMULATION (NMSim) AS A TOOL FOR RESOURCE MANAGEMENT DECISIONS IN NATIONAL PARKS

The National Park Service (NPS) Natural Sounds Program (NSP) office was established in 2000 to help parks manage sounds in a way that protects park resources and provides access and enjoyment for visitors.

Management of NPS acoustical environments is an increasingly important issue, and visualizing noise impacts through models is one method of conveying acoustical information in an approachable way. Models such as NMSim that can simulate sonic conditions in a park can facilitate understanding of complex scenarios, and have great potential to inform the decision-making process. NMSim utilizes topography, ground impedance, ambient sound levels, and custom source spectra to generate spatially explicit animations of vehicle and aircraft noise propagation through space and time. The NSP has been generating NMSim models for several national parks. This presentation will give a case in which NMSim is used to investigate the impacts of different vehicle types (cars, motorcycles, buses, etc.), as well as a second case focusing on aircraft noise.

At Glacier National Park (GLAC) backcountry hikers have reported hearing vehicle and motorcycle noise at remote locations. Several models were generated in NMSim to explore noise propagation of different vehicle classes, including a customized motorcycle noise class based on field measurements of vehicle noise characteristics. The second study focuses on aircraft in Grand Teton National Park (GRTE). NMSim allows researchers to investigate the noise impacts of known flight routes and aircraft types (see Figure 1.).

At both GLAC and GRTE points of interest (overlooks, campgrounds, etc.) were included in the models. This allows for the generation of metrics such as the number of minutes that a single noise event is audible at given locations. These metrics, combined with noise propagation animations, are excellent ways to explain and visually represent noise impacts.

These studies demonstrate that NMSim is capable of providing a wide range of robust quantitative results.  They also underline NMSim's ability to clearly and efficiently convey these results to scientists, planners, and managers alike. 

Figure 1. NMSim output map showing A-weighted decibel (dBA) time histories of aircraft above Grand Teton National Park.