Valles Caldera National Preserve: Acoustic monitoring report
Job JR. 2020. Valles Caldera National Preserve: Acoustic monitoring report. Natural Resource Report. NPS/NRSS/NSNSD/NRR—2020/2137. National Park Service. Fort Collins, Colorado
In 2016, the Natural Sounds and Night Skies Division (NSNSD) received a request to collect baseline acoustical data at Valles Caldera National Preserve (VALL). Between June and July 2017, two acoustical monitoring stations were deployed within the park. Both sites were disturbed by elk with only three days of usable data gathered at VALL002. The goal of the study was to establish a baseline soundscape inventory of the park. This inventory will be used to establish indicators and thresholds of soundscape quality that will support the park and NSNSD in developing a comprehensive approach to protecting the acoustic environment through soundscape management planning. Additionally, results of this study will help the park identify major sources of noise within the park, as well as provide a baseline understanding of the acoustical environment as a whole for use in potential future comparative studies. In this deployment, sound pressure level (SPL) was measured continuously every second by a calibrated sound level meter. Other equipment included an anemometer to collect wind speed and a digital audio recorder collecting continuous recordings to document sound sources. In this document, “sound pressure level” refers to broadband (12.5 Hz - 20 kHz), A-weighted, 1-second time averaged sound level (LAeq, 1s), and hereafter referred to as “sound level.” Sound levels are measured on a logarithmic scale relative to the reference sound pressure for atmospheric sources, 20 µPa. The logarithmic scale is a useful way to express the wide range of sound pressures perceived by the human ear. Sound levels are reported in decibels (dB). A-weighting is applied to sound levels in order to account for the response of the human ear (Harris, 1998). To approximate human hearing sensitivity, A-weighting discounts sounds below 1 kHz and above 6 kHz. For reference, Table 1 provides examples of sound levels measured in parks compared to sound levels of common sound sources.
- Type
- Published Report
- Authors
- Job, Jacob
- Date of Issue
- 2020-06
- Publisher
- National Park Service
- Units
- NRSS , VALL
- Keywords
- Acoustic Monitoring, acoustical monitoring, baseline ambient, natural sound, sound level, Soundscape