The Spatial Structure of the Acoustic Signal Field near the Deep Ocean Bottom Due to a Near-Surface CW Source

Friday, December 5, 1986 12:00 p.m. David Grant Applied Research Laboratories The University of Texas at Austin The spatial structure of the acoustic signal field near the ocean bottom was investigated experimentally. A source near the ocean surface projected a CW tone as it moved along a radial path from a range of 40 km…

Sound Generation by Magnetohydrodynamic and Joule Heating Mechanisms in a Fluid

Friday, 17 October 1986 12:00 p.m. Stephen Schreppler Applied Research Laboratories The University of Texas at Austin When an electrical current passes through a resistive fluid in the presence of a magnetic field, two mechanisms for sound generation are present. The interaction of the electrical current with the magnetic field results in the Lorentz force…

Mechanisms of Hearing – Update 1986

Wednesday, April 2, 1986 4:00 p.m. Craig Wier Speech Communications The University of Texas at Austin Improved micro-manipulation techniques are revealing important new information about transduction mechanisms in hair cells. Following a brief review of the fundamentals of auditory-system anatomy, physiology and biophysics, the results of recent work on hair-cell behavior will be described.

Beamforming Without Plane Waves

Wednesday, March 19, 1986 4:00 p.m. Robert A. Koch Applied Research Laboratories The University of Texas at Austin Practical applications of imaging (beamforming) techniques for inhomogeneous media require an assessment of the constraints imposed by the propagation environment. In this seminar the general features of such constraints will be illustrated with results for an ocean…

Signal Subspace Techniques for Dense Acoustic Array Processing

Wednesday, February 5, 1986 4:00 p.m. T.L.Henderson Applied Research Laboratories The University of Texas at Austin A narrowband approach to signal subspace processing of acoustical signals has been developed over the past several years. Recently, a broadband approach has been developed, requiring the use of dense arrays of hydrophones. Applications will be discussed, for example,…

Ray Theory Construction of Synthetic Seismograms for Ocean Bottom Reflected Acoustic Fields

Wednesday, January 29, 1986 4:00 p.m. David Knobles Applied Research Laboratories The University of Texas at Austin The mathematical aspects of applying classical ray theory to describe acoustic interaction with the seafloor are developed. An integral solution of the time independent wave equation for a point source is first developed. Stationary phase approximations are made…