PROGRESS IN UNDERWATER ACOUSTICS

PROGRESS IN UNDERWATER ACOUSTICS

Edited by

HAROLD M. MERKLINGER Defence Research Establishment Atlantic Dartmouth, Nova Scotia, Canacla

PLENUM PRESS • NEW YORK AND LONDON

Library of Congress Cataloging in Publication Data

Associated Symposium on Underwater Acoustics (1986: Halifax, N.S.) Progress in underwater acoustics.

"Proceedings of the Twelfth International Congress on Acoustics Associated Sym· posium on Underwater Acoustics, held July 16-18, 1986, in Halifax, Nova Scotia, Canada" - T.p. verso.

"Sponsored by the Canadian Acoustical Association" - Pref. Includes bibliographical references and indexes. 1. Underwater acoustics-Congresses. I. Merklinger, Harold, M. II. Associated

Symposium on Underwater Acoustics (1986: Halifax, N.S.) III. Canadian Acoustical Association. IV. Title. QC242.A87 1986 621.389'5 87·11020 ISBN-13: 978-1-4612-9043-8 e-ISBN-13: 978-1-4613-1871-2 DOl: 10.1007/978-1-4613-1871-2

Proceedings of the Twelth International Congress on Acoustics Associated Symposium on Underwater Acoustics, held July 16-18, 1986, in Halifax, Nova Scotia, Canada

© 1987 Plenum Press, New York Softcover reprint of the hardcover Ist edition 1987 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013

All rights reserved

No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher

FOREWORD

IMAGE TRACKS AT HALIFAX

by L.B. Felsen

All living kind much effort spend To cope with their environment Some use their eyes, some use their nose To sense where other things repose. For one group, nothing's more profound Than to explore the world with sound. These audio diagnosticians Go by the name of acousticians.

They regularly meet to check Whether their sonogram's on track. With images stored in their packs, This year they came to Halifax. There they combined with ocean types And each could hear the other's gripes.

A meeting naturally does start Reviewing present state of art. What we found out is where it's at: We cannot hope to match the bat

Computer printouts by the reams Oocument new inversion schemes. Each wiggle gets processed with care To image what is actually there. The ill-posed problem gives us grief, It's science laced with strong belief. The lowly bat has no such doubt: Ill-posed or not, it sorts things out.

After two days of imagery, The sonic thrusters went to sea. The ocean bottom, smooth or rough, Makes tracking sonic signal tough.

Some model modes, some model rays, Some feel that spectra all portrays. Then there are those who with despatch, Take refuge in the ocean wedge.

If things get messy, randomize. What's partly smooth, determinize. You ponder, is it this or that? And wish you were a lowly bat

The meeting's hosts did treat us well. They let the climate cast its spell. No weath'ry hope was placed in vain. We were exposed to wind and rain, We glimpsed blue sky through clouds dispersed. But rainy sequence was reversed: The ocean types would like it wet Yet they got stuck with sun instead.

Each confrence has the same refrain: It has been fun to meet again. May Nova Scotia long survive And let the ocean addicts thrive. To our hosts who labored hard, I offer thanks, ere we depart.

Halifax, Nova Scotia, 14-18 July 1986.

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PREFACE

This book contains the proceedings of the 12th ICA Associated Symposium on Underwater Acoustics held at the Chateau Halifax hotel in Halifax, Nova Scotia Canada, 16-18 July 1986 .. The proceedings is not quite complete, 98 papers were presented, 94 of these are contained in this book.

The 12th International Congress on Acoustics (lCA) itself was held in Toronto during the period 24-31 July 1986. It and the several associated symposia were sponsored by the Canadian Acoustical Association. About three years ago, in 1983, the community of acousticians in Halifax agreed to organize two of these associated symposia under a single organizing committee. The 15th in an annual series of symposia on Acoustical Imaging was one of these, and Prof. Hugh Jones of the Technical University of Nova Scotia took on the management of the technical program. Prof. Leif B j!1lrn!1l of Denmark pressed us to include more emphasis on underwater acoustics and, in the end, I agreed to look after the technical program for a separate symposium for Underwater Acoustics.

I was not alone in this task of organizing the symposium. Assisting immeasurably were Academician L.M. Brekhovskikh (USSR), Prof. Leif Bj!1lrn!1l (Denmark), Dr. R.P. Chapman (Canada), and Dr. W.A. Kuperman (USA), the members of our Technical Committee. Local arrangements were the responsibility of a Local Organizing Committee chaired by Prof. Jones and co-chaired by myself. Other members were Mr. H.W. Kwan, Dr. L.J. Leggat, Mr. David M.F. Chapman, Dr. D.O. Ellis, Dr. N.A. Cochrane and Ms. S. Robertson, with Ms. L. Buckly, Ms. S. Forbes and Mr. R. Raven helping with respect to the hotel.

The original call-for-papers proposed the following technical areas for special attention:

• Underwater Acoustic Imaging • Acoustic Propagation (Deep water, Shallow water, Slope water) • Scattering of Rough Ocean Boundaries • Acoustic Signal Processing and Beamforming • Inverse Methods; and • Acoustics in the Offshore Industry: Petroleum and Fishing.

During the interval between the call-for-papers and the symposium, the falling price of oil on the world market resulted in a noticeable decline of activity in the offshore petroleum industry. This change in emphasis, I believe, 'carried over to our symposium. The greatest emphasis - in terms of papers submitted - was on sound propagation, with a healthy respect paid to the interaction of sound with the ocean bottom.

In the event, 106 papers appeared in the program and, of these, 98 were presented. The authors are to be commended on the quality of their presentations. And the Chairmen did a fine job managing the discussion and keeping to the published'schedule. Over two hundred delegates representing 22 countries attended the symposium. The papers held the attention of delegates to the very end; even the two final afternoon sessions were very well attended.

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The organization of this proceedings does not conform precisely with that of the Symposium itself. The constraints imposed by scheduling two parallel sessions around mealtimes and social functions forced certain groupings that were not based entirely on subject matter. A proceedings is not so constrained, and so the papers are grouped under the following general classifications:

• Sound Scattering from Ocean Boundaries • Sound Scattering from Biological and Other Objects • Acoustic Characterization of the Ocean and Ocean Floor • Sound Propagation in the Ocean

a) General b) Shallow Water c) Slope Water

• Transducers, Radiation and Instrumentation • Signal Processing and Beamforming.

It may be noted that there is no Underwater Acoustic Imaging classification. Most of the papers presented under the imaging classification will appear in the proceedings of the 15th Symposium on Acoustical Imaging, a companion to this volume. The three imaging papers slated for inclusion in the underwater acoustics proceedings fit equally well under one of the above classifications. Within each classification, the order of the papers is essentially the same as for the oral presentations.

Many people assisted in the process of editing this proceedings. Mary Jo Delaney did most of the checking while Linda Kenney did most of the corrections. Assisting with the editing were David Chapman, Dale Ellis, Joe Farrell, Garry Heard, Phil Staal, John Stockhausen and Jim Theriault Thank you all.

Halifax, Nova Scotia Canada October 1986

Harold M. Merklinger

N01E: All rights of the editor have been assigned to The Canadian Acoustical Association, P.O. Box 3651, Station C, Ottawa, Ontario, Canada K1Y 4J1.

ACKNOWLEDGEMENT

The preparation of this book was supported in part by the Nova Scotia Department of Development.

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CONTENTS

OPENING

Opening Address •......................................•.............................................. 1 D. Schofield

SOUND SCATTERING FROM OCEAN BOUNDARIES

Acoustical Visualisation of the Ocean Bottom ......•.......•...................................... 7 L.M. Brekhovskikh, V. V. Krasnoborodko and

V.Ch. Kiriakov

The Sea Bottom Backscattering of Sound (The llistory and Modem State) .................. 15 Yu. Yu. Zhitkovskii

A Unified Description of Wave Scattering at Boundaries with Large and Small Scale Roughness .......••.••....•..••.......................•................... 25

A.G. Voronovich

Validity of the Bom and Rytov Approximations ..•.•••••....••.•.•...•............•.•........... 35 S. Leeman, P. Chandler, LA. Ferrari and DA. Seggie

Multiple Scattering at Rough Ocean Boundaries ................................................. 43 John A. DeSanto

Rough Surface Scattering and the Kirchhoff Approximation ................................... 51 Diana F. McCammon and Suzanne T. McDaniel

lligh Frequency Scattering from Rough Bottoms and the Second Bom Approximation ....................................•.......................................... 57

Stanley A. Chin-Bing and Michael F. Werby

Statistical Characteristics of Acoustic Fields Scattered at the Sea Surface: A Helmholtz-Gulin Model ................................................................. 65

Jerald W. Caruthers, Stanley A. Chin-Bing and Jorge C. Novarini

The Importance of Hybrid Ray Paths, Bottom Loss, and Facet Reflection on Ocean Bottom Reverberation ................•.......................................... 75

Dale D. Ellis and J.B. Franklin

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SCATTERING BY BIOLOGICAL AND OTHER BODIES

The Study of Sound Backscattering from Microinhomogeneities in Sea Water ..................................................................................... 85

VA. Akulichev and VA. Bulanov

Scaring Effects on Fish and Harmful Effects on Eggs, Larvae and Fry by Offshore Seismic Explorations .................................................... 93

John Dalen and Geir Magne Knutsen

Fish Stock Assessment by a Statistical Analysis of Echo Sounder Signals ................. 103 P. N. Denbigh and J. Weintroub

Processing of Fish Echo-Signals for Classification Purpose .................................. 113 Didier Vray and Gerard Gimenez

Broadband Acoustical Scattering by Individual Fish ........................................... 121 Leif Bjpr,,; and Niels Kjaergaard

Multichannel False Color Echograms as a Biological Interpretative Tool .................... 129 NA. Cochrane andDD. Sameoto

Study of the Pseudo-Lamb Wave So Generated in Thin Cylindrical Shells Insonified by Short Ultrasonic Pulses in Water ................................ 137

Maryline Talmant and Gerard Quentin

Scattering of an Acoustic Wave by a Transmission-Loss Tile ................................ 145 Richard J. Brind

Frequency Dependence of the Interaction of Ultrasound with Suspended Sediment Particles .......................................................................... 153

A.S. Schaafsma and AJ. Wolthuis

Sound Scattering in Aqueous Suspensions of Sand: Comparison of Theory and Experiment .................................................................... 161

J. Sheng and AE. Hay

ACOUSTIC CHARACTERIZATION OF THE OCEAN AND THE OCEAN FLOOR

A Combined Seismic Reflection Profiler and Sidescan Sonar System for Deep Ocean Geological Surveys ..................................................... 169

DJ. Dodds and G.BJ. Fader

Signal Processing of Ocean Acoustic Tomography Data ...................................... 181 Duncan Sheldon and G. Clifford Carter

Seismic Profiling with a Parametric, Self-Demodulated Ricker Wavelet .................... 189 T.G. Muir, RJ. Wyber, J.B. Lindberg, and

L.A. Thompson

Remote Acoustic Mapping of a Submarine Spring Plume ..................................... 207 E. Colbourne and A.E. Hay

Acoustic Remote Sensing of the Waveheight Directional Spectrum of Surface Gravity Waves .................................................................... 215

Steven H. Hill

A Pattern Recognition Approach to Remote Acoustic Bottom Characterization ............................................................................. 225

Thomas L. Clarke and John R. Proni

x

Comparative Numerical Study of VLF Signal Propagation Characteristics for Ocean Bottom and Marine Borehole Arrays. . .. . .. . . . . . . . . . . .. . .. 231

G.J. Tango, H.B. Ali, and M.F. Werby

Application of Acoustic Waves and Electrical Conductivity for the Determination of Mechanical Characteristics of Marine Sediments ................... 239

J.P. Longuemard and J M. Daupleix

The Estimation of Density, P-Wave, and S-Wave Speeds of the Top-Most Layers of Sediments ........................................................... 247

S. Levy, J. Cabrera, K. Stinson, D. Oldenburg and NR. Chapman

ETL Reflectivity as a Feature for Recognition of Top-Layer Marine Sediments ................................................................................... 265

Jinsheng Meng andDinghua Guan

Inversion of Ocean Subbottom Reflection Data ................................................. 271 David J. Thomson

An Inverse Method for Obtaining the Attenuation Profile and Small Variations in the Sound Speed and Density Profiles of the Ocean Bottom .......... 279

Subramaniam D. Rajan and George V. Frisk

A Perturbative Inverse Method for the Determination of Geoacoustic Parameters in Shallow Water ............................................................. 287

James F. Lynch, Subramaniam D. Rajan and George V. Frisk

A Synthetic Aperture-Array Technique for Fast Approximate Geobottom Reconnaissance ................................................................ 295

M.F. Werby, GJ. Tango and HE. Ali

Buried Target Reflectivity Evaluation Through an Array of Sensors ......................... 303 R. CarbO Fite and C. Ranz Gue"a

Reflectivity of a Layer With Arbitrary Profiles of Density and Sound Velocity ...................................................................................... 311

P. Cobo, C.RanzandR. CarbO

Sound Speed Profile Inversion in the Ocean .................................................... 319 Unda Boden and John A. DeSanto

A Technique for Modeling the 3-D Sound Speed Distribution and Steady State Water Velocity Field from Hydrophone Data ............................ 329

PD. roung

SOUND PROPAGATION IN THE OCEAN

a) General

A New Form of the Wave Equation for Sound in a General Layered Fluid ................. 337 OA.Godin

Phase Space Methods and Path Integration: The Construction of Numerical Algorithms for Computational Acoustics ................................... 351

Louis Fishman

Predicting Convergence Zone Formation in the Deep Ocean .................................. 361 John J. Hanrahan

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A New Approximate Solution Valid at Turning Points ........................................ 371 Guan Ding-hua and Ling Hui

The Sound Intensities Near the Conjugate Turning Points in an Underwater Sound ChanneL .............................•................................ 379

ZhangRenhe

Modeling Acoustic Waves by Transmutation Methods ........................................ 389 RobertP. GilbertandDavidH. Wood

Beyond What Distance are Finite-Amplitude Effects Unimportant? .......................... 395 Frederick D. Cotaras, David T. Blackstock and

Christopher L. Morjey

Attenuation of Low-Frequency Sound in the Sea: Recent Results ........................... 403 David G. Browning and Robert H. Mellen

On the Calculation of Acoustic Intensity Fluctuations Caused by Ocean Currents ............................................................................. 411

J.S. Robertson, M J. Jacobson and W L. Siegmann

Quick Nonnal Mode Type Starting Fields for Parabolic Equation Models .................. 419 E. Richard Robinson, Hue B. Tran and David H. Wood

A Posteriori Phase Corrections to the Parabolic Equation ..................................... 425 DJ. ThomsonandD.H. Wood

Perturbation Modeling for Ocean Sound Propagation .......................................... 433 MarkD.Duston, GhasiR. VermaandDavidH. Wood

Fast Computation of Perturbed Nonnal Modes ................................................. 439 Dominic Y. Savio andDavidH. Wood

Omnidirectional Ambient Noise Measurements in the Southern Baltic Sea During Summer and Winter ......................................................... 445

RA. Wagstaff and J. Newcomb

Ambient Noise over Thickly Sedimented Continental Slopes ................................. 453 DR. Del Balzo, M J. Authement and D A. Murphy

b) Shallow Water

Some New Challenges in Shallow Water Acoustics ........................................... 461 E.C.Shang

Propagation of Seismic and Acoustic Waves in Horizontally Stratified Media with Stochastically Rough Interfaces ............................................ 473

Henrik Schmidt

The Effect of Variable Roughness of a Granite Seabed on Low-Frequency Shallow-Water Acoustic Propagation .....•.............................................. 485

Philip R. Staal, David M F. Chapman and Pierre Zakorauskas

Ocean Seismo-Acoustic Propagation ............................................................. 493 Tuncay Akal and Finn B. Jensen

Measurements of Wind Dependent Acoustic Transmission Loss in Shallow Water Under Breaking Wave Conditions ..................................... 501

P. Wille, D. Geyer, L. Ginzkey and E. Schunk

xii

Modelling Wind Dependent Acoustic Transmission Loss due to Bubbles in Shallow Water ................................................................. 509

Hans G. Schneider

Fourier and Fresnel Foci and Level Distributions in Interference Fields ..................... 517 DE. Weston

A Model of Sound Propagation in an Open Dock .............................................. 525 Paul J.T. Filippi and Dominique Habault

c) Slope Water

Sound Propagation in a Range-Dependent Shallow Ocean with a Bottom Containing Vertical Sound Speed Gradients ................................... 533

John F. Miller, Anton Nagl and Herbert Uberall

Canonical Propagation Problems for a Wedge Shaped Ocean: L Layered Fluid-Solid Bottom; II. Bottom with Linear Surface Impedance Variation ........................................................................ 541

I.T. Lu and L.B. Felsen

Rigorous Theory of Horizontal Refraction in a Wedge Shaped Ocean ....................... 549 J.M. Arnold and L.B. Felsen

Spectral Decomposition of PE Fields in a Wedge-Shaped Ocean ............................. 557 Finn B. Jensen and HeMik Schmidt

Analytical Solution of the Parabolic Equation for Guided Mode Disappearance at a Critical Depth ......................................................... 565

Allan D. Pierce

Vertical Directionality of Acoustic Signals Propagating Downslope to a Deep Ocean Receiver ..................................................................... 573

N.R. Chapman, JM. Syck and G.R. Carlow

A Theoretical Model of Acoustic Propagation Around a Conical Seamount .................................................................................... 581

Michael J. Buckingham

Experimental Bearing Shifts as Evidence of Horizontal Refraction in a Wedge-Like Ocean ....................................................................... 589

R. Doolittle, A. Tolstoy and M. Buckingham

TRANSDUCERS, RADIATION AND INSTRUMENTATION

Underwater Soundbeams Created by Airborne Laser Systems ............................... 595 Allan D. Pierce and H.-A. Hsieh

Optical Generation of Sound: Experiments with a Moving Thermoacoustic Source. The Problem of Oblique Incidence of the Laser Beam ............................................................................. 603

Yves H. Berthelot and Ilene J. Burch-Vishniac

Acoustic Measurements and Applications of Kinetic Impacts on Ice ......................... 611 Philippe de Heering

Axial Focusing by Phased Concentric Annuli ................................................... 619 H D. Mair and D A. Hutchins

xiii

Computer Simulation of Beam. Patterns for a Sonar Phased Cylindrlcal Array ............................................................................ 627

A. Stepnowski, J. Szczucka and L. Pankiewicz

Some Aspects of Transducer Design by Finite Element Techniques ......................... 639 JR. Dunn

A 10-kW Ring-Shell Projector .................................................................... 647 G.W. McMahon and BA. Armstrong

Beamforming with Acoustic Lenses and Filter Plates .......................................... 651 Robert L. Sternberg

Hydrophone Using a Fiber Fabry-Perot Interferometer ....................................... 657 S. Ueha, N. Wang, M. Ohgaki and M. Okujima

An Improved Method for Fluid Structure Interactions •••..........•........................... 665 DJ.W. Hardie

Acoustic Pressure Radiated from Heavy-Fluid Loaded Infinite Plate Driven by Several Point Forces.. . .. ... .....••... .. . ..... . .. .... .. . .. . .. . .. . .. . . . . .. . .. . .. 673

Jacqueline Larcher

Transfer Properties of a Fluid Loaded Elastomer Layer ....................................... 681 Daniel Vaucher de la Croix

Parametric Acoustic Array Application Using Liquids with Low Sound Speed ................................................................................. 689

A.W.D. Jongens and P.B. Runciman

SIGNAL PROCESSING AND BEAMFORMING

Signal Processing for Precise Ocean Mapping ...............•.................................. 697 ~ivindHeier

An Underwater Acoustic Position Fixing System for Precise Low Range Use .................................................................................. 707

Raymond Wood

Improvement of Underwater Acoustic Localization by Coherent Processing ................................................................................... 717

M. Zakharia, P. Arzelies, M.E. Bouhier, JP. Corgiatti andB. Fouche

A Beam. Steering Process for Seismic Data ...........•.......................................... 727 Scott P. Cheadle andD.C. Lawton

Frequency Frequency-Rate Spectral Analysis ................................................... 735 MAPrice

Space-Time Processing. Environmental-Acoustic Effects ..................................... 743 W M.Carey and W.B. Moseley

An Efficient Method of Dolph-Chebyshev Beamforming ..................................... 759 A. Zielinski

Multipath Processing for Improved Detection on a Long Vertical Array ..................... 765 Donald A. Murphy and Donald R. Del Balzo

xiv

Bearing Estimation of a Single Monochromatic Plane Wave with a Linear Receiving Array ........•..•..•..................................................... 773

Didier Billon

Iterative Methods for Enhancement of Multichannel Data ..................................... 783 OleE.Naess

Linear Prediction for Sensor Recovery in Line Array Beamforming •.•.•..•.•....................•................................................ 793

R.S. WalkerandDN. Swingler

An Algorithm for High-Resolution Broadband Spatial Processing ........................... 801 J. Newcomb and RA. Wagstaff

MISSING ABSTRAerS .......................................................................... 809

PROORAM ......................................................................................... 811

AUlHOR INDEX .................................................................................. 825

SUBmer INDEX ................................................................................. 833

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