Hawai'i Volcanoes National Park: Acoustic monitoring report 2019

Meyer, Erik

doi:10.36967/2312657

In 2018, the Natural Sounds and Night Skies Division (NSNSD) received a technical assistance request (4938) to collect baseline acoustic data at Hawai‘i Volcanoes National Park (HAVO) to pair with a concurring study tracking aircraft over the park. From March to October 2019, acoustical monitoring systems were deployed at three study sites in the park, HAVO002 (Mauna Loa) and HAVO002B (Halemaʻumaʻu) during the Spring, and HAVO009A (Puʻu Huluhulu/ New Lava Flows) during the Summer and Fall. Combined, these three seasons of acoustic measurements provide park managers with baseline information about the acoustic environment, including existing ambient sound levels, time-above noise level metrics, and audibility of a variety of sound sources in the park. Aircraft and vehicles were the most frequently heard noise sources at all sites during spring, summer, and fall measurement periods. However, these two sources contributed less than 15% of noise audibility across the entire monitoring period. Overall, across all sites and seasons, existing median ambient sound levels (LA50) ranged from 20.2 dB–32.4 dB during the daytime and 16.8–39.8 dB during the nighttime. Natural ambient sound levels (LAnat) ranged between 19.0–32.0 dB during the day and 16.7–39.8 dB at night. Increased natural ambient sound levels during day and night varied by location and were likely caused by diurnal winds and site-specific ecology that drives insect and bird activity. Over the two measurement periods, during the daytime, hourly LAeq sound levels exceeded 52 dBA level, a level at which interpretive programs are likely to be interrupted, less than 3.0 % of the time.

Hawai'i Volcanoes National Park: Acoustic monitoring report 2019

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