No description available.

No description available.

Aperture synthesis, as its name implies, synthesises an aperture by storing successive echoes obtained from a moving platform and by processing the results as if they had been obtained from a multi-element array enables a high azimuth resolution to be obtained from a physically small array. The technique has been highly successful in radio astronomy, and in both satellite and aircraft borne radar. However the use of this technique has been very limited in the sonar environment mainly because of difficulties of maintaining a stable track under water and problems of under-sampling of the aperture arising from the relatively slow velocity of acoustic waves in water. The thesis describes a study of the application of the synthetic aperture technique to sonar, highlighting some of these difficulties and possible means of overcoming them. A study has also been made the application of the bathymetric technique, a technique for measuring the height of objects on the sea bed, to synthetic aperture sonar. In addition to the theoretical work and computer simulation, an experimental system has been built in a water tank measuring some 9m by 5m by 2m deep in order to test a number of the algorithms and some good results have been obtained.

No description available.

x, 270 leaves, : ill., tables ; 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, Dept. of Electrical Engineering, 1975

This study investigated the effectiveness of utilizing acoustic measures as an objective tool in monitoring speech errors and providing visual feedback to enhance speech training and aural rehabilitation of children with hearing impairment. The first part of the study included a comprehensive description of the acoustic characteristics related to the speech deficits of a hearing impaired child. Results of a series of t-tests performed on the experimental measures showed that vowel length and the loci of formant frequencies were most relevant in differentiating between correctly and incorrectly produced vowels, while voice onset time along with measures of Moment 1 (mean) and Moment 3 (skewness) obtained from speech moment analysis, were related to consonant accuracy. These findings, especially the finding of an abnormal sound frequency distribution shown in the hearing impaired child's consonant production, suggest a link between perceptual deficits and speech production errors and provide clues to the type of compensatory feedback needed for aural rehabilitation. The second part of the study involved a multiple baseline design across behaviours with replication across three hearing impaired children to assess the efficacy of treatment with acoustic signals as visual feedback. Participants' speech articulations following traditional speech training and training using spectrographic and RMS displays as visual feedback (referred to as 'visual treatment') were compared, with traditional non-visual treatment followed by visual treatment on one or two targets in a time-staggered fashion. Although no statistically significant difference on the experimental measures was found between the two training approaches based on perceptual assessment, some objective acoustic measures revealed more subtle changes toward normal speech patterns with visual treatment as compared to a traditional approach. Further acoustic-perceptual studies with a larger sample size and longer experimental period are needed to better understand the general and long-term effectiveness of visual treatment.

Thesis (Ph. D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Robert C. Maher. Includes bibliographical references (leaves 100-106).

Thesis (Ph.D.)--University of Texas at Dallas, 2007. / Includes vita. Includes bibliographical references.

Diss. (sammanfattning) Stockholm : Karol. inst., 2001. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Adelaide, 1990. / Typescript (Photocopy).