<p> This interdisciplinary study examines episodic memory and instrumental timbre as structural analogs, and explores the potential of their relationships within a compositional framework. The paper begins by framing contemporary models of memory and timbre within the notion of topology&mdash;the ways in which patterns of components are interrelated within an abstract space, and how those patterns remain consistent or degrade over time. I proceed to probe the ways in which both memorial and timbral processes are constructed upon spectra of stability and coherence, and examine the role of &ldquo;place&rdquo; in the establishment of these spectra. My analysis occurs at one possible intersection of neurology, psychoacoustics, spectral composition, and the poetics of memoir. The second half of the paper is concerned with how these theories are applied in practice within my composition fragments in autumn for cello trio and electronics. A personal history, structural analysis, and close reading of the piece demonstrates the possibilities of memory as a compositional/timbral process, as well as the difficulties and instabilities that are inherent in such an endeavor. Through both creative and scholarly modes of inquiry, I pose to myself and the reader: How can music function as an act of translation in regard to something as opaque and personal as memory? How can the resonant properties of an instrument be treated with the same complexities and nuances of a remembering mind? How might these processes of memory move away from modes of &ldquo;story-telling&rdquo; and toward a more abstract exploration of topological contours? How do these models of timbre and memory function as prescriptive frameworks for composing, and where do they break down?</p>

No description available.

The zooplankton communities off the north east coast of Scotland, Wee Bankie sand-banks, were studied with traditional net samples and for the first time, for this area, with acoustic methods. A series of zooplankton samples were collected during June 2010 and March/June 2011 together with a set of physical parameters of the water column. Taxonomic analysis of the collected samples enabled the characterisation of zooplankton communities. Neritic communities with oceanic influence were found along the north east coast of Scotland and over the Wee Bankie with spatial variability associated with higher densities of zooplankton inshore. Temporal variability was associated with the expected succession of dominant copepods from spring to summer. An appropriate scattering model, Distorted Wave Born Approximation, was used to predict the target strength of the major zooplanktonic groups and so solve the forward problem to verify a plankton separation algorithm. The algorithm isolated weak scattering targets of zooplankton using three frequencies (38, 120 and 200 kHz) and was used to study the zooplankton spatial distribution during June 2008-2011 in relation to the physical characteristics of the water column. Model predicted target strength for the major zooplanktonic groups was sensitive to orientation for large organisms and material properties for both copepods and euphausiids. The Wee Bankie waters were thermally stratified, with June 2011 the least stratified of all years. Depths of observed maximum backscatter varied in relation to the pycnocline depth and tended to be deeper in offshore stations. The estimated biomass from the observed backscatter increased from 2008 to 2011 but spatial patterns varied from year to year. Although, estimated biomass across years reduced with increasing maximum fluorescence and surface to bottom temperature difference, the same relationship was not evident within year.

<p> This dissertation investigates the occurrence of an intermediate stage, termed a covert contrast, in the acquisition of Mandarin Tone 2 (T2) and Tone 3 (T3) by adult speakers of American English. A covert contrast is a statistically reliable distinction produced by language learners that is not perceived by native speakers of the target language (TL). In second language (L2) acquisition, whether a learner is judged as having acquired a TL phonemic contrast has largely depended on whether the contrast was perceived and transcribed by native speakers of the TL. However, categorical perception has shown that native listeners cannot perceive a distinction between two sounds that fall within the same perceptual boundaries on the continuum of the relevant acoustic cues. In other words, it is possible that native speakers of the TL do not perceive a phonemic distinction that is produced by L2 learners when that distinction occurs within a phonemic boundary of TL.</p><p> The data for the study were gathered through two elicitations of tone production, a longitudinal analysis, and two perception tasks. There were three key findings. First, both elicitations showed that most of the L2 participants produced a covert contrast between T2 and T3 on at least one of the three acoustic measures used in the study. Second, the longitudinal analysis reveals that some L2 participants progressed from making a covert contrast to a later stage of implementing an overt one, thereby supporting the claim that making a covert contrast is an intermediate stage in the process of acquiring a L2 phonemic contrast. Third, results of the perceptual tasks showed no reliable difference in identifying and discriminating Mandarin T2 and T3 on the part of the L2 learners who produced a covert contrast and those who produced an overt contrast, indicating that there was no reliable difference in the two groups&rsquo; ability to perceive the target tones. </p><p> In all, the occurrence of a covert contrast in the process of acquiring Mandarin T2 and T3 suggests that L2 acquisition of a tonal contrast is a gradient process, one in which an intermediate step occurs before a L2 learner reaches the final stage of implementing an overt contrast that is perceived as target-like by the native speakers of the TL.</p>

<p> Apex predators are important indicators of ecosystem health, but little is known about the population structure of Bigg&rsquo;s killer whales (<i> Orcinus orca</i>; i.e. &lsquo;transient&rsquo; ecotype) in western Alaska. Currently, all Bigg&rsquo;s killer whales in western Alaska are ascribed to a single broad stock for management under the US Marine Mammal Protection Act. However, recent nuclear microsatellite and mitochondrial DNA analyses indicate that this stock is likely comprised of genetically distinct sub-populations. In accordance with what is known about killer whale vocal dialects in other locations, I sought to evaluate Bigg&rsquo;s killer whale population structure by examining the spatial distribution of group-specific call types in western Alaska. Digital audio recordings were collected from 33 encounters with Bigg&rsquo;s killer whales throughout the Aleutian and Pribilof Islands in the summers of 2001-2007 and 2009-2010. Recorded calls were perceptually classified into discrete types and then quantitatively described using 12 structural and time-frequency measures. Resulting call categories were objectively validated using a random forest approach. A total of 36 call types and subtypes were identified across the entire study area, and regional patterns of call type usage revealed three distinct dialects, each of which corresponding to proposed genetic delineations. I suggest that at least three acoustically and genetically distinct subpopulations are present in western Alaska, and put forth an initial catalog for this area describing the regional vocal repertoires of Bigg&rsquo;s killer whale call types.</p>

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

There are two focal points of this thesis: the acoustics of seagrass and the acoustical properties of encapsulated bubbles for underwater noise abatement. The acoustical properties of seagrass have applications in mine hunting, shallow water sonar, and environmental acoustic remote sensing. In order to optimize these applications, a predictive model of acoustic propagation in seagrass beds is sought. Previous laboratory research has indicated that the tissue acoustic properties of seagrass as well as the tissue physical structure and entrained air masses inside the leaves contribute to the overall acoustic behavior. The present research utilized a glass laboratory resonance tube to find the low frequency (1 kHz-4 kHz) acoustic compressibility of two species of seagrass, Thalassia testidinum and Halodule wrightii. By using a mixture of finely divided seagrass tissue suspended in seawater, the bulk moduli of the seagrass species were extracted. In the second section, encapsulated bubbles were analyzed as a method of abating underwater anthropogenic noise sources, since these sources, including marine piledriving and oil and gas exploration and production, pose potential harmful effects to marine life. Previous research, which used an array of rubber-shelled encapsulated bubbles, found the attenuation from these bubbles in be in close accordance with an existing encapsulated bubble model. Experiments were performed in a small laboratory resonance tank, a large outdoor acoustic tank, and at Lake Travis Test Station (LTTS) in order to determine the effects of varying an encapsulated bubble's wall thickness and fill material on bubble resonance frequency and damping. Results found that increasing the wall thickness tended to increase the balloon resonance frequencies measured in the small tank, which was strongly correlated to the frequency of maximum noise reduction in the large outdoor test tank and LTTS tests. The addition of polyester fibers and aluminum wool as fill materials decreased both the resonance frequency and quality factor, whereas helium-filled filled encapsulated bubbles had an increased resonance frequency but decreased quality factor as compared with air-filled bubbles. The resonance quality factor and void fraction further proved to affect the noise reduction near bubble resonance in the outdoor acoustic tank and LTTS tests. The measurements made with a single bubble in a small laboratory tank were correlated to measurements with a full-size system composed of many bubbles operating in open water. / text

No description available.

No description available.