ATTENTIVE LISTENING IS AN IMMERSIVE EXPERIENCE , and in national park settings it can amplify visitor awareness of resources and their value. Noise disrupts this experience. Accordingly, the sounds of a park unit and superb conditions for hearing them are signatures of park integrity and authenticity. Quiet environments encourage relaxation, observation, learning, and contemplation. For indoor settings, these values are expressed in the protective architectural noise standards that apply to libraries, classrooms, concert venues, and churches (American National Standards Institute, Standard S12.2). In protected natural areas, noise-free environments also provide outstanding opportunities to perceive and identify the sounds of nature, encouraging visitors to expand their auditory as well as visual horizons. The compelling benefits of natural quiet for park visitors reinforce the importance of noise management for preserving and restoring ecological integrity. Acoustical communication is vital for many species, and hearing alerts animals to nearby events, even when they are sleeping.

Acoustic monitoring is essential for managing noise, and it is a powerful tool to document patterns of wildlife activity and visitor use. Many animals reveal their presence and advertise their behavior using sound. Unattended recording is noninvasive: weeks of data can be obtained with minimal human presence and instrument footprint, and animals do not have to be captured or tagged. Audio recordings can chronicle changes in wildlife behavior in response to visitor use or revised management practices. Acoustic monitoring is an efficient way to track almost any form of traffic: hikers, all-terrain vehicles, snowmobiles, boats, automobiles (and their types), and aircraft. Finally, acoustic monitoring can identify sources of noise and document daily and seasonal patterns in ambient sound levels.

Audio recordings can chronicle changes in wildlife behavior in response to visitor use or revised management practices.