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Using Soundscapes to Measure Biodiversity, Habitat Condition, and Environmental Change in Aquatic EcosystemsBen L Gottesman (8098112) 06 December 2019 (has links)
<div>Biodiversity loss is the silent crisis of the 21st century. Human activities are drastically altering the diversity of life on Earth, yet the extent of this transformation is shrouded by our limited information on biodiversity and how it is changing. Emerging technologies may be suited to fill this information gap, and as a result increase our capacity to measure and manage natural systems. Acoustic monitoring is a remote sensing technique that is rapidly reshaping the temporal and spatial scales with which we can assess animal biodiversity. Through recording and analyzing soundscapes—the collection of sounds occurring at a given place and time—we can assess biodiversity, habitat condition, and environmental change. However, the relationships between soundscapes and these three ecological dimensions are still in the early phases of categorization, especially in aquatic systems. </div><div><br></div><div>This dissertation investigates how soundscapes can be used to measure biodiversity, habitat condition, and environmental change in aquatic habitats. It addresses several knowledge gaps: First, I develop a framework for classifying unknown sounds within a soundscape, which I use to measure the acoustic diversity and dynamics within a tropical freshwater wetland. Second, I demonstrate that soundscapes can reflect the resilience of animal communities following disturbance events. Altered soundscapes revealed that Hurricane Maria, which swept through Puerto Rico in September 2017, impacted dry forest animal communities more than adjacent coral reef communities. Third, in kelp forest habitats off the coast of California, USA, I showed that soundscape variables correlated with ecological variables associated with regime shift in kelp forests, including urchin density, kelp cover, and fish diversity. Overall, this dissertation demonstrates that soundscape recording and analysis is a promising way to assess the ecological conditions of aquatic systems. </div>
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DEVELOPMENT OF SOURCE-PATH MODELS TO SYNTHESIZE PRODUCT SOUNDS OF AN OUTDOOR HVAC UNITWesaam Lepak (9193604) 03 August 2020 (has links)
Outdoor heating, ventilating, and air-conditioning (HVAC) units emit a significant amount
of noise, which may lead to poor sound quality and a perceived low product quality. It is the job
of the noise control engineer to reduce the undesired noise and improve the sound quality of the
outdoor HVAC unit to decrease consumer annoyance. There is great interest in developing a
detailed and accurate acoustic model of the outdoor HVAC unit so that the sound of the outdoor
HVAC unit can be listened to before the unit is constructed. Having an acoustic model which can
synthesize sounds allows the noise control engineer to evaluate and improve the sound quality of
the outdoor HVAC unit during the design process, without the need for extensive prototyping.
Acoustical holography methods will be used to identify and localize noise due to the fan, and other
significant noise sources, to visualize the sound field. In the current study, an acoustic model is
described which can be used to model the noise due to structural radiation and vortex shedding of
the outdoor HVAC unit’s rotating fan blades, one of the top contributors to the unit’s overall noise
level. This moving source model simulates the Doppler effect which occurs when the blade moves
towards and away from a receiver. The results from this moving source model is shown for
different source signals, including sinusoidal, bandpass random, repeating random, and sinusoidal
with time-varying frequency source signals. The parameters of this moving source model will be
optimized to reproduce the experimental results, including the power spectral densities, tonal
power component, and auralizations.
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