IMAGE TRACKS AT HALIFAX by L.B. Felsen All living kind much effort spend Some model modes, some model rays, To cope with their environment Some feel that spectra all portrays. Some use their eyes, some use their nose Then there are those who with despatch, To sense where other things repose. Take refuge in the ocean wedge. For one group, nothing's more profound Than to explore the world with sound. If things get messy, randomize. These audio diagnosticians What's partly smooth, determinize. You ponder, is it this or that? Go by the name of acousticians. And wish you were a lowly bat They regularly meet to check Whether their sonogram's on track. The meeting's hosts did treat us well. With images stored in their packs, They let the climate cast its spell. This year they came to Halifax. No weath'ry hope was placed in vain. There they combined with ocean types We were exposed to wind and rain, And each could hear the other's gripes. We glimpsed blue sky through clouds dispersed. A meeting naturally does start But rainy sequence was reversed: Reviewing present state of art. The ocean types would like it wet What we found out is where it's at: Yet they got stuck with sun instead. We cannot hope to match the bat Each confrence has the same refrain: Computer printouts by the reams It has been fun to meet again.

Table of Contents:
Opening.- Opening Address.- Sound Scattering from Ocean Boundaries.- Acoustical Visualisation of the Ocean Bottom.- The Sea Bottom Backscattering of Sound (The History and Modern State).- A Unified Description of Wave Scattering at Boundaries with Large and Small Scale Roughness.- Validity of the Born and Rytov Approximations.- Multiple Scattering at Rough Ocean Boundaries.- Rough Surface Scattering and the Kirchhoff Approximation.- High Frequency Scattering from Rough Bottoms and the Second Born Approximation.- Statistical Characteristics of Acoustic Fields Scattered at the Sea Surface: A Helmholtz-Gulin Model.- The Importance of Hybrid Ray Paths, Bottom Loss, and Facet Reflection on Ocean Bottom Reverberation.- Scattering by Biological and Other Bodies.- The Study of Sound Backscattering from Microinhomogeneities in Sea Water.- Scaring Effects on Fish and Harmful Effects on Eggs, Larvae and Fry by Offshore Seismic Explorations.- Fish Stock Assessment by a Statistical Analysis of Echo Sounder Signals.- Processing of Fish Echo-Signals for Classification Purpose.- Broadband Acoustical Scattering by Individual Fish.- Multichannel False Color Echograms as a Biological Interpretative Tool.- Study of the Pseudo-Lamb Wave So Generated in Thin Cylindrical Shells Insonified by Short Ultrasonic Pulses in Water.- Scattering of an Acoustic Wave by a Transmission-Loss Tile.- Frequency Dependence of the Interaction of Ultrasound with Suspended Sediment Particles.- Sound Scattering in Aqueous Suspensions of Sand: Comparison of Theory and Experiment.- Acoustic Characterization of the Ocean and the Ocean Floor.- A Combined Seismic Reflection Profiler and Sidescan Sonar System for Deep Ocean Geological Surveys.- Signal Processing of Ocean Acoustic Tomography Data.- Seismic Profiling with a Parametric, Self-Demodulated Ricker Wavelet.- Remote Acoustic Mapping of a Submarine Spring Plume.- Acoustic Remote Sensing of the Waveheight Directional Spectrum of Surface Gravity Waves.- A Pattern Recognition Approach to Remote Acoustic Bottom Characterization.- Comparative Numerical Study of VLF Signal Propagation Characteristics for Ocean Bottom and Marine Borehole Arrays.- Application of Acoustic Waves and Electrical Conductivity for the Determination of Mechanical Characteristics of Marine Sediments.- The Estimation of Density, P-Wave, and S-Wave Speeds of the Top-Most Layers of Sediments.- ETL Reflectivity as a Feature for Recognition of Top-Layer Marine Sediments.- Inversion of Ocean Subbottom Reflection Data.- An Inverse Method for Obtaining the Attenuation Profile and Small Variations in the Sound Speed and Density Profiles of the Ocean Bottom.- A Perturbative Inverse Method for the Determination of Geoacoustic Parameters in Shallow Water.- A Synthetic Aperture-Array Technique for Fast Approximate Geobottom Reconnaissance.- Buried Target Reflectivity Evaluation Through an Array of Sensors.- Reflectivity of a Layer With Arbitrary Profiles of Density and Sound Velocity.- Sound Speed Profile Inversion in the Ocean.- A Technique for Modeling the 3-D Sound Speed Distribution and Steady State Water Velocity Field from Hydrophone Data.- Sound Propagation in the Ocean.- a) General.- A New Form of the Wave Equation for Sound in a General Layered Fluid.- Phase Space Methods and Path Integration: The Construction of Numerical Algorithms for Computational Acoustics.- Predicting Convergence Zone Formation in the Deep Ocean.- A New Approximate Solution Valid at Turning Points.- The Sound Intensities Near the Conjugate Turning Points in an Underwater Sound Channel.- Modeling Acoustic Waves by Transmutation Methods.- Beyond What Distance are Finite-Amplitude Effects Unimportant?.- Attenuation of Low-Frequency Sound in the Sea: Recent Results.- On the Calculation of Acoustic Intensity Fluctuations Caused by Ocean Currents.- Quick Normal Mode Type Starting Fields for Parabolic Equation Models.- A Posteriori Phase Corrections to the Parabolic Equation.- Perturbation Modeling for Ocean Sound Propagation.- Fast Computation of Perturbed Normal Modes.- Omnidirectional Ambient Noise Measurements in the Southern Baltic Sea During Summer and Winter.- Ambient Noise over Thickly Sedimented Continental Slopes.- b) Shallow Water.- Some New Challenges in Shallow Water Acoustics.- Propagation of Seismic and Acoustic Waves in Horizontally Stratified Media with Stochastically Rough Interfaces.- The Effect of Variable Roughness of a Granite Seabed on Low-Frequency Shallow-Water Acoustic Propagation.- Ocean Seismo-Acoustic Propagation.- Measurements of Wind Dependent Acoustic Transmission Loss in Shallow Water Under Breaking Wave Conditions.- Modelling Wind Dependent Acoustic Transmission Loss due to Bubbles in Shallow Water.- Fourier and Fresnel Foci and Level Distributions in Interference Fields.- A Model of Sound Propagation in an Open Dock.- c) Slope Water.- Sound Propagation in a Range-Dependent Shallow Ocean with a Bottom Containing Vertical Sound Speed Gradients.- Canonical Propagation Problems for a Wedge Shaped Ocean: I. Layered Fluid-Solid Bottom; II. Bottom with Linear Surface Impedance Variation.- Rigorous Theory of Horizontal Refraction in a Wedge Shaped Ocean.- Spectral Decomposition of PE Fields in a Wedge-Shaped Ocean.- Analytical Solution of the Parabolic Equation for Guided Mode Disappearance at a Critical Depth.- Vertical Directionality of Acoustic Signals Propagating Downslope to a Deep Ocean Receiver.- A Theoretical Model of Acoustic Propagation Around a Conical Seamount.- Experimental Bearing Shifts as Evidence of Horizontal Refraction in a Wedge-Like Ocean.- Transducers, Radiation and Instrumentation.- Underwater Soundbeams Created by Airborne Laser Systems.- Optical Generation of Sound: Experiments with a Moving Thermoacoustic Source. The Problem of Oblique Incidence of the Laser Beam.- Acoustic Measurements and Applications of Kinetic Impacts on Ice.- Axial Focusing by Phased Concentric Annuli.- Computer Simulation of Beam Patterns for a Sonar Phased Cylindrical Array.- Some Aspects of Transducer Design by Finite Element Techniques.- A 10-kW Ring-Shell Projector.- Beamforming with Acoustic Lenses and Filter Plates.- Hydrophone Using a Fiber Fabry-Perot Interferometer.- An Improved Method for Fluid Structure Interactions.- Acoustic Pressure Radiated from Heavy-Fluid Loaded Infinite Plate Driven by Several Point Forces.- Transfer Properties of a Fluid Loaded Elastomer Layer.- Parametric Acoustic Array Application Using Liquids with Low Sound Speed.- Signal Processing and Beamforming.- Signal Processing for Precise Ocean Mapping.- An Underwater Acoustic Position Fixing System for Precise Low Range Use.- Improvement of Underwater Acoustic Localization by Coherent Processing.- A Beam Steering Process for Seismic Data.- Frequency Frequency-Rate Spectral Analysis.- Space-Time Processing, Environmental-Acoustic Effects.- An Efficient Method of Dolph-Chebyshev Beamforming.- Multipath Processing for Improved Detection on a Long Vertical Array.- Bearing Estimation of a Single Monochromatic Plane Wave with a Linear Receiving Array.- Iterative Methods for Enhancement of Multichannel Data.- Linear Prediction for Sensor Recovery in Line Array Beamforming.- An Algorithm for High-Resolution Broadband Spatial Processing.- Missing Abstracts.- Program.- Author Index.