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No description available.

No description available.

Killer whales inhabiting coastal waters of the northeastern Pacific are listed under the Canadian Species at Risk Act, which requires the identification of critical habitats for the recovery of their populations. Little is known about their distribution during the winter and what areas are important for their survival during these months. Passive acoustic monitoring is a valuable complementary method to traditional visual and photographic surveys although it has seldom been used to study killer whales and there are limitations in practice. There is a need to develop tools and protocols to maximize the efficiency of such studies. In this thesis, long-term acoustic data collected with autonomous recorders were analyzed 1) to assess the performance of two types of analysis (Manual and Long Term Spectral Averages) for detecting and identifying killer whale calls and to compare the effects of using two different duty cycles (1/3 and 2/3); and 2) to investigate the seasonal occurrence of different killer whale populations at two sites off the west coasts of Vancouver Island and Washington: Swiftsure Bank and Cape Elizabeth. Both the use of Long Term Spectral Averages and a lower duty cycle resulted in a decrease in call detection and resolution of call identification, leading to underestimations of the amount of time the whales spent at the site. A compromise between a lower resolution data processing method and a higher duty cycle (and vice-versa) is therefore suggested for future passive acoustic monitoring studies of killer whales. Killer whale calls were detected on 186 days at Swiftsure Bank and on 39 days at Cape Elizabeth. The seasonal occurrence of killer whales at Swiftsure Bank highlights its importance as a killer whale hotspot, with year-round presence of Southern Residents and British Columbia Transients, Northern Residents in spring and fall, and California Transients on rare occasions. These results support the expansion of Southern Resident’s critical habitat to include Swiftsure Bank. Temporal habitat partitioning between Resident populations was observed at Cape Elizabeth, with Southern Residents detected from January through June and Northern Residents from July to September. These results show that Northern Residents use the southern parts of their range more frequently than previously thought. Both Transient populations were frequently detected throughout the year, suggesting habitat overlapping. / Graduate

One class of Surface Acoustic Wave (SAW) devices employs reflecting arrays to determine device characteristics. Dots of metal film and grooves have been used as reflectors; reflection is caused by the mechanical discontinuity. This research project is a study of an alternative reflector, the thin metal dot, which reflects by interacting with the electric field that accompanies the SAW on a piezo-electric material. Experimental work is done on Y-cut LiNbO₃, a common SAW material, the aim being to characterise the reflection mechanism sufficiently to design devices, particularly on this material. Reflectivities of a large range of dot sizes is reported. Velocity change due to dots, another parameter required in device design, is also measured. In addition, holes in a metal film, physically the opposite of dots, are also studied. A theorectical model is developed to predict the behaviour of dots in devices. For a <strong>Z</strong>-propagating wave in LiNbO₃, the SAW velocity for completely free and completely metallised surfaces were used to specify the properties of the material. For propagation in other directions on the surface, particularly near the <strong>X</strong> direction, a different acoustic mode, the Leaky Surface Wave (LSW), has an influence on SAW reflections, and the model also requires the LSW velocities under the same two conditions. The model uses these parameters, together with dot geometry, to determine reflectivity in any direction and velocity change due to the dots. The results agree well with experiments. A device (a RAC) is designed using this model, to bring out any unforseen difficulties in the use of dot arrays. The device performed as expected except for some unanticipated attenuation in the arrays, which can almost certainly be predictably allowed for in future designs, being broadband and not very severe.

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No description available.

The focus of this thesis is the relationship between the articulation ofspeech and the acoustics of produced speech. There are several problems thatare encountered in understanding this relationship, given the non-linearity,variance and non-uniqueness in the mapping, as well as the differences thatexist in the size and shape of the articulators, and consequently the acoustics,for different speakers. The thesis covers mainly four topics pertaining to thearticulation and acoustics of speech.The first part of the thesis deals with variations among different speakersin the articulation of phonemes. While the speakers differ physically in theshape of their articulators and vocal tracts, the study tries to extract articula-tion strategies that are common to different speakers. Using multi-way linearanalysis methods, the study extracts articulatory parameters which can beused to estimate unknown articulations of phonemes made by one speaker;knowing other articulations made by the same speaker and those unknown ar-ticulations made by other speakers of the language. At the same time, a novelmethod to select the number of articulatory model parameters, as well as thearticulations that are representative of a speaker’s articulatory repertoire, issuggested.The second part is devoted to the study of uncertainty in the acoustic-to-articulatory mapping, specifically non-uniqueness in the mapping. Severalstudies in the past have shown that human beings are capable of producing agiven phoneme using non-unique articulatory configurations, when the artic-ulators are constrained. This was also demonstrated by synthesizing soundsusing theoretical articulatory models. The studies in this part of the the-sis investigate the existence of non-uniqueness in unconstrained read speech.This is carried out using a database of acoustic signals recorded synchronouslyalong with the positions of electromagnetic coils placed on selected points onthe lips, jaws, tongue and velum. This part, thus, largely devotes itself todescribing techniques that can be used to study non-uniqueness in the sta-tistical sense, using such a database. The results indicate that the acousticvectors corresponding to some frames in all the phonemes in the databasecan be mapped onto non-unique articulatory distributions. The predictabil-ity of these non-unique frames is investigated, along with verifying whetherapplying continuity constraints can resolve this non-uniqueness.The third part proposes several novel methods of looking at acoustic-articulatory relationships in the context of acoustic-to-articulatory inversion.The proposed methods include explicit modeling of non-uniqueness usingcross-modal Gaussian mixture modeling, as well as modeling the mappingas local regressions. Another innovative approach towards the mapping prob-lem has also been described in the form of relating articulatory and acousticgestures. Definitions and methods to obtain such gestures are presented alongwith an analysis of the gestures for different phoneme types. The relationshipbetween the acoustic and articulatory gestures is also outlined. A method toconduct acoustic-to-articulatory inverse mapping is also suggested, along withva method to evaluate it. An application of acoustic-to-articulatory inversionto improve speech recognition is also described in this part of the thesis.The final part of the thesis deals with problems related to modeling infantsacquiring the ability to speak; the model utilizing an articulatory synthesizeradapted to infant vocal tract sizes. The main problem addressed is related tomodeling how infants acquire acoustic correlates that are normalized betweeninfants and adults. A second problem of how infants decipher the number ofdegrees of articulatory freedom is also partially addressed. The main contri-bution is a realistic model which shows how an infant can learn the mappingbetween the acoustics produced during the babbling phase and the acous-tics heard from the adults. The knowledge required to map correspondingadult-infant speech sounds is shown to be learnt without the total numberof categories or one-one correspondences being specified explicitly. Instead,the model learns these features indirectly based on an overall approval rating,provided by a simulation of adult perception, on the basis of the imitation ofadult utterances by the infant model.Thus, the thesis tries to cover different aspects of the relationship betweenarticulation and acoustics of speech in the context of variations for differentspeakers and ages. Although not providing complete solutions, the thesis pro-poses novel directions for approaching the problem, with pointers to solutionsin some contexts. / QC 20111222 / Computer-Animated language Teachers (CALATea), Audio-Visual Speech Inversion (ASPI)

Typescript (Photocopy) / viii, 138 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Depts. of Applied Mathematics and Mechanical Engineering, 1990

Design culture is tentatively embracing the acoustic conditions and auditory awareness of spaces and objects, thus creating new opportunities for spatial sound practitioners. This thesis examines the making of seven spatial sound design projects in diverse milieux and an eighth project - the establishment of an electroacoustic studio within a school of architecture and design. The projects and the studio are considered models for the ways in which electroacoustic practices might advance the auditory spatial awareness of students and researchers in the academy, and the general community through an interlocking program of teaching, research and events. The creation of the projects and establishment of the studios also articulate a transformation in my own practice from composer to design researcher. Five of the projects are intended to engender in listeners a greater awareness of the acoustic environment and the auditory spatial qualities of those environments, whi ch listeners daily inhabit. Supporting these project studies is a discussion on issues and conditions of making and materials to elucidate my approach to creating spatial sound designs in diverse milieux. Two of the projects investigated the auditory spatial awareness of different communities in Melbourne, with the view of establishing ideas about the auditory culture and the actual environments of that experience. The final project is a facility to house a community of practitioners who aspire to privilege the auditory design and experience of space, through a series of research, teaching and performance activities. While evaluating just how my practice transformed over the course of the projects, I also propose that the combination of the Studio's main elements is critical to the advancement of sound-based research and design as a design discipline. Note to audio and visual materials - This thesis was accompanied by a custom-built multi-channel sound playback environment using Max/MSP and Flash. For further details on this player and Quicktime files, contact lawrence.harvey@rmit.edu.au.