Methods for managing soundscape quality: Evidence from Denali National Park and Preserve

Abstract

The purpose of the United States national park system is to preserve resources unimpaired for the enjoyment of future generations. At Denali National Park (DENA), high levels of air tour traffic and air transportation present challenges to preserving wilderness character. Accordingly, the park attached high priority to measuring visitor impressions of soundscape quality. Visitors in four distinct settings rated the acceptability of five randomly chosen recordings of aircraft noise. We used a cumulative link mixed model to fit visitor’s response to acoustic and nonacoustic factors. The negative effects of increased noise were moderated for visitors who were interested in taking an air tour. To be conservative, we examined visitors uninterested in an air tour and found the probability of rating aircraft noise as unacceptable at 54 dB LAeq, 30 s or higher was 26%. For context, noise above 55dB is incompatible with outdoor, rural activities. Visitor response predictions were joined to a spatial model of aircraft noise propagation to create a map depicting the acceptability of aircraft noise in DENA’s frontcountry area. The map can be used to forecast the range of soundscape conditions park visitors are exposed to, inform hiking recommendations for visitors, and evaluate park management zones.