Preserving and restoring authentic acoustic environments that will inspire the American public

摘要

Legislative mandates and the high public value placed on U. S. National Park units demand that the National Park Service (NPS) manage acoustical environments for superb quality. Design standards for bedrooms, musical performance venues, and religious sanctuaries establish precedents for management of high quality conditions for indoor acoustical environments, but the long history of outdoor noise management has focused on how much noise can communities tolerate before health effects or high levels of annoyance are evident. The quest to preserve or restore superb environmental quality led NPS to very different research questions, methods for characterizing environments, and management criteria. To adequately characterize natural acoustical conditions, NPS had to develop lightweight, low-power packages capable of measuring very low sound levels for long periods of time. To characterize subtle intrusions of noise into wilderness and other protected natural areas, NPS had to devise methods for measuring and predicting the audibility of noise sources at long ranges from the source. To understand the opportunity costs of lost listening opportunities, NPS had to stimulate research into the ecological functions of hearing for wildlife and the psychological and behavioral significance of sounds for park visitors. In addition to research results, tools are emerging from these efforts that will be useful outside the boundaries of national parks. NPS and the Volpe Transportation Center collaborated to develop more flexible methods of noise modeling to support rapid evaluation of alternative management plans for air tours and surface transportation in national parks. NPS developed a geospatial model that generalizes sound level measurements made at over 300 sites to offer a map predicting natural and existing sound levels for the coterminous U. S. In addition to these tools, it may be hoped that NPS can contribute to a broader reevaluation of criteria for managing communities that considers the potential for acoustical environments to enhance health and human experience.