The Las Vegas Infrasound Array (LVIA) is a network of eleven infrasound sensors deployed from November 2019 through September 2022. While ambient infrasound noise in high and low-noise rural environments has been well characterized, little attention has focused on similar characterization in urban areas with presumed higher background noise levels. The LVIA long-term deployment provides an unprecedented opportunity to study urban infrasound and low frequency audio (20–500 Hz). In addition, large scale shutdowns due to the COVID-19 pandemic provide the ability to discriminate between background noise sources as closures reduced human-generated noise while natural signals remained stable. Within this presentation we will provide an overview of the LVIA installation, focusing on data quality. In addition, we will discuss comprehensive background noise models in urban regions, focusing on presenting probability density functions (PDFs) and median, 5th percentile, and 95th percentile amplitude values to evaluate variations in frequency and amplitude. We will summarize observed trends in background noise over time, highlighting sharp declines in acoustic power following COVID-19 shutdowns. Both sets of analyses will be combined to evaluate periodicities in urban acoustics throughout the city of Las Vegas. [ SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.]

Recent studies have demonstrated the utility of seismic stations for recording acoustic signals from events of interest. Here, we present an analysis of seismoacoustic arrivals originating from weekly controlled munition disposals at the McAlester Army Ammunition Plant (McAAP) in Oklahoma over a period of nine months during 2019. These arrivals were recorded on 121 temporary and permanent seismic stations across Oklahoma and surrounding states. Arrivals were identified by a human analyst team. Because of its consistency and duration, the McAAP dataset provides an opportunity to study the spatial and temporal variability of infrasound propagation because it relates to seasonally variable atmospheric conditions. Recorded arrivals identify an acoustic shadow zone ranging in distance from 50 to 200 km of the source, along with seasonal directional shifts in the stratospheric duct. Acoustic raytracing is used to produce comparisons of predicted and observed arrival dynamics, concluding that current atmospheric specifications do not capture the full complexity of the atmosphere.