Aircraft noise dose-response relations for national parks

Abstract

An analysis of visitor survey responses and concurrent noise exposure was performed using data from ten sites in four scenic U. S. National Parks. Data collection was structured to learn the effects of air-tour aircraft noise and high-altitude jet noise on the experience of park visitors at scenic overlooks and on short hikes. The analysis utilized multilevel logistic regression and resulted in six doseresponse relations: two responses (annoyance and interference with natural quiet), paired with three response dichotomizations (slightly or more, moderately or more, and very or more). Each of those six relations retained the same set of regression predictors. Individual-visitor Leq from all aircraft (averaged over the visitor duration at the site) proved to be the most reliable/accurate predictor of all noise dose metrics tested. The relation with visitor Leq was significantly strengthened by inclusion of three additional dose-related predictors: the energy-percentage due to tour helicopters for each visitor, the same due to fixed-wing tour aircraft, and the interaction of these two percentages. In addition, the relation was also strengthened by inclusion of the following context variables: Scenic overlook or short hike, natural quiet very important (or not) to that visitor, visitor group includes only adults (or not), and first-time visit at that site (or not). For a given noise exposure, visitors expressed more negative response regarding interference with natural quiet than regarding annoyance. In addition, visitor response to a given dose of air-tour noise was less severe when there were low-to-moderate levels of high-altitude jet noise present. V C 2011 Institute of Noise Control Engineering.

ICBEN review of research on the biological effects of noise 2011-2014

“…For instance, exposure-response relationships were derived for both annoyance and interference with the experience of natural quiet due to aircraft overflights in several US national parks. [ 241 ] Also, the annoyance induced by scooters and motorbikes in urban streets and parks was explored. [ 242 ] It was found, additionally, in a laboratory situation that aircraft noise — in particular, helicopter noise — led to annoyance, and affected solitude and tranquility in comparison to natural sounds in subjects watching virtual national park scenes.…”

The relationship between aircraft noise exposure and day-use visitor survey responses in backcountry areas of national parks

“…The backcountry data and dose-response models are intended to complement the frontcountry data and models. 10 However, there are a number of key aspects that differ between the studies that must be noted. First, a number of data collection protocols in the current study were implemented to address the added complexity of backcountry research and improve upon prior research.…”

“…The model identified for the backcountry data differs from that identified for the frontcountry data, most notably in the noise dose metrics. 10 The frontcountry model includes dose metrics of L AeqTresp , P EnHelos , and P EnProps and the interaction term P EnHelos * P EnProps . In contrast, the backcountry model identified herein includes dose metrics of L AE , %TAud, P EnHelos , and P EnProps.…”

“…Analyzing site as the "random" component of the multilevel regression avoids underestimates of prediction uncertainty, which can happen when site-to-site variabilities are not included in the regression equation. 10 Each model of the dichotomous response variables includes "site" as a random component, plus additional dose and mediator variables for each visitor…”

“…The analysis and resulting dose-response relationships showed differences between overlook and short-hike visitor evaluations of overflight noise and that evaluations are further mediated by the aircraft source type(s) and visitor ratings of the importance of natural quiet, whether they have visited the site before, and whether they visited with children. 10 Additionally, the researchers recommended the study of backcountry sites with day-and overnight use as the highest priority for data needs. 11 Remote areas may have lower background sound levels that elevate the salience of aircraft noise, and visitors engaging in longer trips in remote areas may have higher expectations for environmental quality.…”