Electroacoustical simulation of listening room acoustics for project ARCHIMEDES

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Electroacoustical simulation of listening room acoustics for project ARCHIMEDES
Bech, Søren
Published in:
Acoustical Society of America. Journal
Link to article, DOI:
10.1121/1.2027447
Publication date:
1989
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Citation (APA):
Bech, S. (1989). Electroacoustical simulation of listening room acoustics for project ARCHIMEDES. Acoustical
Society of America. Journal, 86(S1), S2-S2. https://doi.org/10.1121/1.2027447

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PROGRAM OF
The 118th Meeting of the AcousticalS ociety of America
Adam's Mark Hotel ß St. Louis, Missouri ß 27 November-1 December 1989
MONDAY EVENING, 27 NOVEMBER 1989 ST. LOUIS D, 7:00 TO 9:00 P.M.
Tutorial on Architectural Acoustics
Mauro Pierucci, Chairman
Departmento f Aerospacaen d EngineeringM echanicsS, an DiegoS tate UniversityS, an Diego,
California 92182
TUI. Architecturala cousticsT:h e forgodtitmene nsionE. wart A. Wetherill (Wilson, lhrig, and Associates,
lnc., 5776 Broadway,O akland, CA 94618)
The basic considerationso f architeclural acouslics---isolation from unwanled noise and vibration, control
of mechanicasl ystemn oise,a nd room acousticsd escilgena-r-l-ya erxee amllp lifiedin Sabinc'sd esignf or
BostonS ymphonyH all. Openedin ! 900,t hish all iso neo f theo utstandinsgu ccessiens m usicaal cousticsY.e t,
asw e approachth e hundredtha nniversaryo f Sabine'sfi rste xperimentsa,c ousticacl haracteristicrse main one
of the leastc onsidereda spectso f buildingd esign.T his is due, in part, to the difficultyo f visualizingt he
acouslicaol utcomeo f designd ecisionsc,o mplicatedb y individuajlu dgmenta st o whatc onstitutegso oda cous-
tics. Howlaecvke or,f tah ec omprehensivtee achingp rogramr emainst he dominantp roblem.S ignificant
advanceso ver the past 2 or 3 decadesin measuremenat nd evaluationh ave refinedt he ability to design
predictabilitya nd to demonsIratea cousticalc oncernst o others. New such as sound intensity
measurementnse, wd escriptorfso r rooma cousticpsh enomenaa,n dt her efinemetn o f recordinga, nalysisa,n d
amplificationt echniquesp rovidef reshi nsightsin to the behavioro f soundi n air and other media.T heset opics
are reviewedw ith particulare mphasiso n the needf or a comparablea dvancein translationo f acousticp rinci-
plesi nto buildingt echnologies.
Sl J. AcoustS. oc.A m.S uppl.1 , VoL8 6, Fall1 989 118thM eetingA: cousticaSlo cietyo f America S1
TUESDAY MORNING, 28 NOVEMBER 1989
ST. LOUIS BALLROOM C, 8:00 A.M. TO 12:00 NOON
SessionA . Architectural Acoustics I: Electronic Room Simulation for Production and Reproduction
Elizabeth A. Cohen, Cochairman
CharlesM . Salter AssociatesIn, c., 130 Sutter Street,S an Francisco,C alifornia 94101
J. ChristopherJ affe,C ochairman
JaffeA cousticIsn, c., 114A WashingtoSnt reet,N orwalk,C onnecticu0t6 854
Chairman's Introduction4:00
SpecialT ribute--8:05
Theodore John Schultz--A Tribute
Presentbeyd:E warAt .W ether(il Wl ilsolnh,r iga, ndA ssocia5t7e 7s6,B roadwOaya,k lanCd,a liforn9ia4 618)
Invited Papers
8:15
A1. Electroacousticasl imulationo f listeningr oom acousticsfo r projectA RCHIMEDES. S6rcn Bcch (The
AcousticsL aboratoryT, echnicaUl niversityo f Denmark,B uilding3 52,D K-2800 Lyngby,D enmark)
ARCHIMEDES is a psychoacoustircess earchp roject,f undedu ndert he EuropeanE UREKA scheme.
Threep artnerss haret he worki nvolvedT: he AcousticsL aboratoryo f The TechnicaUl niversityo f Denmark;
Banga ndO lufseno f Denmark;a ndK EF Electronicosf EnglandI.t s primaryo bjectis t o quantifyt hei nfluence
of listeningro oma cousticosn the timbreo f reproducesdo undF. or simulationo f thea cousticosf a standard
listeningro om,a n electroacoustsice tuph asb eenb uilt in an anechoicc hamberT. he setupi s basedo n a
computemr odeol f thel isteningro om,a ndi t consistosf a nmnbeor f loudspeakeprso sitioneodn a n imaginary
spheres urroundintgh e positiono f the tests ubjectT. he setuph asb eend esignefdo r the highesdt egreeo f
flexibility.T his includesth e possibilityo f simulationo f directivityc haracteristicosf normald omesticlo ud-
speakerasn da bsorptiocno efficienotsf thes urfaceosf thel isteningro om.T hisp aperi s a presentatioonf the
systemw, iths peciaelm phasiosn t hep sychoacoustibcaacl kgrounodf t hed esignT. hisw ill includea discussion
of choiceo f experimentaplr ocedurete, sts timuli,a ndt ests ubjectass w ella sp urposbe uiltl oudspeakearsn dt he
DSP system.
8:45
A2. The psychoaeousticosf loudspeakesr oundr eproduction--Pasta chievementasn dp resentp roblemsF. loyd
E. Toole (Division of Physics,N ational ResearchC ouncil, Ottawa, Ontario K1A 0R6, Canada)
The designo f loudspeakeriss graduallyb eingp ut on a scientificb asisA. rt and intuitionh aveg ivenw ay to
engineeringg uidelinesa st he relationshipbse tweenp erceptionasn d technicalm easurementhsa veb eene luci-
dated.I ndeed,w ithin limitedc ircumstancelso, udspeakercsa nb e designedto meets pecifice ngineeringd esign
objectivesw, ithc onsiderabcleo nfidencien howt heyw ill bes ubjectiveleyv aluatedI.n practiceh, owevera, ll of
ther elevanct onditionasr en otc ontrolleda, nds everafla ctorsc onspirteo precludeu niversasla tisfactioanm ong
listenersM. ost of the uncertaintya ppearst o bei n the interactionsb etweenlo udspeakersr,o oms,l istenersa, nd
programm aterial.T his paperr eviewsth e presenst tateo f knowledgea,n d outlinesth e areasm osti n needo f
furtherw ork.I t isc leart hat additionapl sychoacousticdaalt aa nds uitablete chnicailn novationcsa na lleviate
someo f the remainingp roblems.O thers,t hough,m ay be better treatedb y standardization.
9:15
A3. RODS---An advanced approach to electronic reverberation enhancement. Peter W. Barnett (AMS
AcousticsL, td., 52 ChaseS ideS outhgateL, ondonN 14 SPA, United Kingdom)
This paperw ill brieflyr eviewt he recenth istoryo f reverberatioenn hancemenatn d then examineth e
processiensv olvedin thed evelopmenotf t heR ODS ( Reverberation-on-DemaSnyds temc) oncepTt.h et heory
and implementationo f the RODS conceptw ill be explainedf,o llowedb y examplesa nd resultso f recent
installations.
S2 J. Acoust.S oc. Am. Suppl.1 , Vol. 86, Fall 1989 118th Meeting:A cousticaSl ocietyo f America S2
9:45
A4. (cid:127)plali(cid:127)tion usingv oicea ndm usic(cid:127)s the sourceJ. ohn Meyer (Meyer SoundL aboratories2,8 32S an
PabloA venue.B erkeleyC, A 94702)
A source-independteencth niquteo measuraec curateltyh ea mplitudaen dp hasere sponsoef s ounds ystems
in concerht allsi sd iscusseMd.e asuremenmtsa yb em aded uringli vep erformanceosr eventsu, singm usico r
voicea st he tests ignalsC. orrelatioins shownb etweenth e impulse(cid:127)e sponsea ndt he resultso btainedu sing
musics ignalsA. n equalizetrh atc orrectsfo r manyr oomr esonanceins b otha mplitudea ndp hases imultaneous-
ly hasb eend evelopedT.h e effecot f thise qualizeor n concerst ystemisn an existingv enueis shown.
10:15
A5. A spatial soundp rocessofro r headphonea nd Ioudsl(cid:127)eakerr eproductionW. illiam L. Martens, Gary
S. Kendall,a ndM artin D. Wilde (SoundSpherIen, c., 1030D avisS treet,E vanstonI,L 60201)
A spatials oundp rocessofro r stereoh cadpbonea nd loudspeakerre productionis describedth at can posi-
tion sounde lementsw ithin a threc-dimensionrael verberanst paces urroundingth e listener.S patialm otiono f
sounds ourcesin three dimensioniss createdb y dynamicf ilteringb asedo n head-relatedtr ansferf unctions.
Additionalf iltersa nd delayl inesc apturea ir absorptiona nd Dopplers hiftinga s the propagationti me is
manipulatefdo r bothd irecta ndi ndirects oundT. he spatiotempordails tributiono f earlyr eflectioniss c aptured
for a givens ource/listeneorr ientationT: he gain,d elay,a nd directionafli lteringo f simulatedre flectionasr e
responsivteo changesin thes pecifiedp ositiona ndo rientationo f thes ounds ourcea ndt he listener'sh eadi n the
simulatede nvironmenTt.h e spatiapl rocessocra nb eu sedf or headphonree productiouns inga head-tracking
devicea, ndc ana lsob e usedi n moret ypicalr eproductions ettingss ucha sl ivingr oomsw ith stereolo udspeak-
ers.I n the latterc asea, dditionapl rocessinigs e mployedto stabilizeth e stereoim agea ndp roducea spatially
diffuser everberanst urrounde ffecto vera wide rangeo f listeningp ositions.
10:45-11.'00
Break
Contributed Papers
11:00 11:15
A6. Binaural simulationt echniquef or scale modeling.N . Xiang and
J. Blauert( Lehrstuhlf ar AllgemeineE lektroteehniku ndA kustik,R uhr
A7. On the model order for the identification of acoustical systems.
Universit(cid:127)it, D-4630 Bochum 1, FederalR epublico f Germany)
Nobuo Koizumi (NTT Human Interface Laboratories, Tokyo 180,
Japan}a ndR ichardH . Lyon (Departmento f MechanicaEl ngineering,
Rooms imulatiofno r thep urposoef predictinagc oustibce havioar nd
MIT, CambridgeM, A 02139)
qualityh asr ecentlyb ecomea populart opici n rooma cousticsA.t the
Ruhr Universityt,h ee xperiencoef theb inauralh umanl isteneirn a room
The pole/zerom odela ndt hef initei mpulsere spons(eF IR) modela re
simulationu singb othp hysicaal ndc omputemr odelingh asb eena uthenti-
useda s systemm odelsfo r the identificatioonf unknowna cousticasly s-
callyr ecreatedT. hisp aperr eportso n thel atests tageo f thep resenwt ork
tems.T he size of the model is particularlyi mportanti n discrete-time
in binauralr ooms imulationu singa scaledd ownp hysicaml odel,w herea
implementatioans i t determinetsh e convergencrea teo f adaptationa nd
sensitivem iniatured ummy head with accuratclys caledp innae( scale
capacityo fr eal-timep rocessinTgh. eo rdero ft hep ole/zerom odeils r elat-
factor1 :10)s ervesa sa receivetro picku p them odels oundfi eld.A versa-
ed to modal distributiono f systemsw hile the order of the FIR model
tile PC-baseds ystemm easuresth e binaurali mpulser esponseisn model
dependosn its dampingfa ctor.E ffectiveo rderso f bothm odelsa ree sti-
spacea ccordingto the m-sequencter ansforma nd alsoe arficao ut the
matedf rom the statisticapl ropertieosf acousticasly stemsIn. a three-
convolutiono f ther oom-impulsree sponsewsi th ancchoics peecho r music
dimensionale nclosure,i ts volume and reverberationt ime are used for
signalsA. n especiallyw ide broadbandu ltrasonictr ansmitters ystemis
estimationI.t iss hownt hat, whenm odald ensityo f the systemis low, such
necessartyo providet he desiredc omplexs timulationo f the soundf ield.
asi n a smalle nclosurea, nd frequencyra ngei s narrow,p ole/zerom odel-
After the necessarsyi gnalp rocessingth, e resultings ignalsc anb c listened
ing can greatlyr educet he modelo rder. [Work supportedb y NTT Hu-
to binaurally via headphones[. Work supportedi n part by Deutsche
man InterfaceL aboratoriesT, okyo 180,J apan.]
Forsehungsgemeinsch] aft.
11:30-12:00
Panel Discussion
S3 J. Acoust.S oc. Am. Suppl.1 , VoL8 6, Fall 1989 118th Meeting:A cousticaSl ocietyo f America S3
TUESDAY MORNING, 28 NOVEMBER 1989
ST. LOUIS BALLROOM G, 8:00 A.M. TO 12:00 NOON
SessioBn . PhysicaAl cousticIs: ScatteringP, ropagationD,i ffractiona, ndR eflection
JulianD . Maynard, Chairman
DepartmoefPn th ysiPcse,n nsylvSatnaitaUe niversUitnyi,v ersPiatyrk P, ennsyilav1 a6n8 02
ContributedP apers
Kristenssoann dS . Strrm, J. Acoust.S oc.A m. 64, 917-936 ( 1978) ; G. S.
8:00
Sammelmanna nd R. H. Hackman, J. Acoust. $oc. Am. 82, 324-336
B1. Consequencoefs t hea coustibc ipolarc ouplingtso largea specrta tio
( 1987) ]. Thesea rticlesc onsidesr cattererisn nonattenuatingliq, uidm e-
scatterersR. oger H. Hackman( PhysicalA cousticsB ranch,N aval
dia.W heno bjectsb uriedin sedimenatr ec onsideredh,o wevers, ediment
CoastaSl ystemCs enter,P anamaC ity, FL 32407)
attenuationin troducedfu ndamentallny ewf eaturesin to the description
of thes catterinpgr ocessT.h e interactiono f an incidenpt lanew avew ith
It hasb eens uggestetdh at a planew avea xiallyi ncidento n a large
the sediment-seawatienrt erfaced istortsth e phase-amplitudreel ationo f
aspecrta tios catterecro upletso botht hei nsonifieedn do f thes catterer
the wave incidento n a scattererin the sedimentT. he descriptiono f the
andt ot hee ndi n theg eometrisch adowa,t lowk D/2 (Dis eithert hem inor
scatterinogf thesein homogeneowuasv esr equiresth e introductioonf
axiso f a spheroido r the diameteor f a cylinder)[ Williamse t al., J.
new, suitably modified basiss tatesf or the solutiono f the scattering
Acoust.S oc.A m. 85, 2372-2377 (1989) ]. This effecti s concretelye stab-
problemT.h em odificatioonf t heT -matrixa ndw aveguidthee oriedse vel-
lisheda, ndi tse xperimentcaol nsequencaeresd iscusseind s omed etailA.
opeda t theN avalC oastaSl ystemCse nteris discusseadn da numerical
novelc losed-formex pressioins d erivedf or t(cid:127)e axisymmetriecl,a sticr e-
studyo f thes catterinbgy a thins phericaslh ellb uriedin an attenuating
sponsoef a largea specrta tiot argetth atd irectlyin corporattehse b ipolar
liquids edimenits presented.
couplinogf thea coustiacn de lasticfi eldsT. hef ormo f thef inale xpression
is,i n somer espectss,i milart o thato btainedfr omt heg eneralizegde omet-
ric theoryo f diffractionin theh igh-frequencliym it for elastics phereasn d
cylindersa,l thoughth ep hysicaals sumptioanrse q uited ifferentS. imple,
approximaetes timateosf thep arameteirnsv olvedin thise xpressioanre
8:45
obtaineda nd comparedw ith a T-matrixc alculation.
B4. High-frequencayc oustiscc atterinfgr oma doublyp eriodice llipsoidal
surface: Neumann boundary conditions. Garner C. Bishop and
Judy Smith( Naval UnderwaterS ystemCs enter,N ewport,R I 02840)
8:15
An exacts olutioni s obtainedf or the scattero f an acousticp lanew ave
B2. The acoustiscc atteringb y a submergeedl,a stics phericasl hell:T he
from an infinites urfacec onstructefdr om a doublyp eriodica rrayo f infi-
transitionf rom thin to thick shellsG. ary S. Sammelmanann d Roger
nitea ndp aralleel llipticasl emicylindeNrse. umannb oundarcyo nditions
H. Hackman( PhysicaAl cousticBs ranch,N aval CoastaSl ystems
arei mposeadn dt heH elmholtz-Kirchhoifnft egraul sedto calculatteh e
scatterepdr essurfeie ld.F redholmin tegrael quationosf thef irsta nds ec-
Center, PanamaC ity, FL 32407)
ond kind are used to calculate the surface field. Numerical calculations
A fundamentalolyri enteadn alysiosf t hep oles tructuroef t hea coustic
are performetdo determinteh e effectso f geometripca rameterosn the
scatterinmga trixin t hel ow-t oh igh-frequenrecgyi on(0 <kay1<0 00a) sa
scatterepdr essurfeie lda ndt hed ependenocfe t hes urfacfeie ldo nt het ype
functioonf m oden umberd,e nsitya,n ds oundsp eefdo rs everaslh eltlh ick-
ofF redholmin tegrael quationu sedR. esultsa rea lsoc omparewd itht hose
nessehsa sb eenp reviousplyr esente[dJ. AcousSt. oc.A m.S uppl1. 83,
for scatteringfr om a sinusoidasl urface.
S94( 1988);S uppl1. 84,S 185( 1988);S upplI. 85,S 95( 1989)].T he
threem ositn terestinrges ultosf thisa nalysiwse re:( 1) Duet o fluidl oad-
ing,t hev acuuman tisymmetLraicm bm odaeo a ndt her igidF ranzm odes
switcht ails top roducae s ubsonaioc _ m odeth atr esembltehse v acuum
9:00
antisymmetLriacm bm odea t lowk a anda na o+m odeth atr esemblaeo s
ath ighk a;( 2) them id-frequenecnyh ancemeonfa t thins helils a ssociat-
BS. Contributions to the form function for elastic spheresb ased on a
edw ith thisb ifurcationo f thea ntisymmetriLca mbw ave[ J. AcoustS. oc.
producte xpansiono f the S function:N umericalt ests.P hilip L. Marston
Am. 85, 114--124( 1989)] ; and (3) the existencoe f strongt hickness
(Departmento f PhysicsW, ashingtonS tateU niversity,P ullman,W A
resonanceass sociatewdi th the existencoef regionso f negativeg roupv e-
99164)
locityfo rt het hirda ntisymmetLriacm bw aveo na thins phericsahl ellI.n
thisp resentatitohne,t rajectorioefst h ep oleosf t hea coustSic m atrixa sa
Associatewd ith the scatteringp hases hift6 , of the nth partialw ave
functiono f thet hicknesosf thes hella ref ollowedA. unifiedp ictureo f the
fora s pheroef r adiuas ist hef unctioSn, (x) = exp[ 2i6n ] , wherex = ka.
resonancsetr ucturoef a sphericaslh elal sa functioonf sheltl hicknesiss
A theoremfr omc lassicaslc atteringth eoryl eadst o aproducet xpansioonf
presenteadn, dt hei mportancoef tails witchinogf thee lastica ndd iffrac-
Sn, which allows for multiple resonances[ P. L. Marston, J. Acoust. $oc.
tlyed egreeosf freedomin thet ransitiofnro ma thickt o a thins helli s
Am. Suppl.I 84, S185( 1988) ]. ThisS , remainsm anifestlyu nitarye ven
for multipler esonancels a nd clarifiesim plicita ssumptionosf RST. The
illustrated.
elasticc ontributionfs,(cid:127) to the formf unctiond ependo n complexk a pole
locationsx.(cid:127)=--X.t -- i(F(cid:127)t/2) and * whereX (cid:127)t >0 , F(cid:127)>O, and *
denotesc omplex conjugation.I n the case of only two resonances
(l = 1,2),i tmayb es hownth atf ,(cid:127) =f(cid:127)t +f,,2 d-f l,i (cid:127)l +f(cid:127). The f,,(cid:127) have
8:30
a Breit-Wigner form f(cid:127)
B3. Acoustici nteractionsw ith buriedo bjects.R aymond Lim and Roger
--x-- (i/2)F(cid:127)t ] and (cid:127), is the phases hifta ssociatewdi th the back-
H. Hackman (Physical AcousticsB ranch, Naval Coastal Systems
groundfa ctoro f S(cid:127). The term f(cid:127) is a terma ssociatewdi th the polea t
Center, PanamaC ity, FL 32407)
-- x,*,itn thel efth alfo ft hec omplekxa planew hilef (cid:127)i.(cid:127)l isa ni nteraction
term.T he effecto f f(cid:127) is smalli f F(cid:127) <X,t. This approximatioonf f(cid:127) is
The theoreticadl escriptiono f the scatteringfr om objectsn earm edi-
confirmedb y numericalc omparisonw ith the f(cid:127), basedd irectlyo n the
um boundariehs asb eent hes ubjecot f a numbero f recenta rticles[ e.g.,G .
S4 J.A cousSt.o cA. mS. upp1l., V ol8. 6,F all1 989 118thM eetingA:c ousticSaol cietoyf A merica S4
producet xpansionT.h ec omparisoanls os howsth ato missioonf thet erm sentatiofonr s ource-excited-time-harpmreosnsiucfr iee ldisn t hep resence
f((cid:127)., i canin troduscueb stanetriraol rfos rx betweXe,n(cid:127) a ndX ,2,. [Work of a thin elastics phericasl helli mmersedin differenti nteriora nd exterior
supportedb y ONR. ] fluidsT. he newf ormulatioind entifiedsi rectlyth et ravelinwg avews ith
theirm ultipleen circlemeonft tsh es helbl ye xtendinthge 0 domainfr om
itsc onvention0a<l 0(cid:127)<(cid:127)r rangew ith periodicitcyo nstraintins tot he un-
bounded( multisheeted)d omainw ithout thesec onstraintsT. he new for-
mulatioanl sos ystematiztehset reatmenotf s phericcaal psa ndo thertr un-
cateds ectionPse. riodicitfyo r thec losesdh elils r ecoverebdy s umming
9:15 contributionfrso ma ni nfinitea rrayo f images ourcelso catedin then on-
physicalp ortion0 < 0 and0 > rro f thea ngulasr paceT.h er igorousso lu-
B6. Lips causticsin light backscatterefdro m an acousticalllye vitated
tion is obtainedb y synthesiosv er a complexs pectracl ontinuuma, nd
sl(cid:127)heroidalw ater drop. Harry J. Simpsona nd Philip L. Marston
variousa lternativree presentatioanrse d erivedfr omi t. Speciaalt tentionis
(Departmenot f PhysicsW, ashingtoSnt ateU niversityP, ullmanW, A
givent o rigorouhsi gh-frequencays ymptotifco rmst hatd escribteh ew ave
99164-2814)
phenomenina t ermso fi ncidenatn dg eometricarlelyf lecterda yf ieldsa,n d
Cuspd iffractiocna tastrophtehsa to penu pr oughlytr ansverstoe t he alsoi n termso f surfacgeu idedra yf ieldsT. hel attera ree xcitedb yp hase
propagatiodnir ectionar ek nownto existf or bothl ighta nds ound[P . L. matchinogf thei ncidenrta yf ieldt o thet ravelinwg avem odeisn thes hell,
MarstonJ,. AcousSt. ocA. m.8 1,226-232(1 987)].T heym ayb ep ro- andt heyr eachth eo bservebry p hasem atchedd etachmen[ st eea, lsoP, . L.
ducedb y reflectingh igh-frequencsyo undf rom curveds urfacesIn. the MarstonJ, . AcoustS. oc.A m. 83, 25-37 (1988)]. The phasem atching
presenrte searcah c, loselrye latedc austiicn whichth ec uspc urvejso int o appliesto directlye xcitedle akyw avesa s well as to wavesth at decay
forma p airo fl ipsis s tudiedT.h isc austiwca sp redictetdoe xist[ J.F . Nye, initiallyin tot hef luid;t hel attera ree xcitedfr oma n exteriosr ourcbe y
Nature3 12,5 31-532( 1984)] in lightb ackscatterferdo mh orizontally evanescenttu nneling.[ Work supportedb y the O(cid:127)ce of Naval Research
illuminateodb lated ropso f waterp, rovidetdh ea xisr atioq = D/H was and David Taylor ResearchC enter.]
withinc ertainra ngesT.h ea ssociaterady sa red iffracteadt thed rop's
surfacea ndh aveo nlyo nei nternarl eflectionA. s q is increaseadb oveth e
criticalv alueq 4(cid:127) 1.31a ssociatewdi tha hyperboliucm bilicf ocals ection,
thec uspp ointsa t thee ndso f thel ipsc austiwc erep redictetdo mergein
the backwardd irectiona t a lips event whenq = qL(cid:127)1.42. For
qL(cid:127) < q < qc2 (cid:127) 1.58,n o causticfso r thisc lasso f ray aree xpectedw hilea 10:f10
seconldip se vento ccursa t qL2 - Observationosf f arfields catterinfgro m
levitatedd ropss upportN ye's analysisa nd illustratea mechanismfo r B9. The opticali llusiono f sound.B radfordL . Swartz (Communication
producinglip s causticsT.h e observebda ckscatterinisg w eakf or q DisordersC, entralM ichiganU niversity,M t. PleasantM, I 48859)
betweenq L(cid:127) andq (cid:127)2. [Work supportedb y ONR. ]
The graphicd epictiono f soundis nota straightforwarmd atter.S ta-
tionaryr epresentationuss ingl ines,w aveso, r circlesle avet he notiono f
movemen(te itherp articleo r energy)a ndp ressurfelu ctuationws ithint he
wavet o ther eader'sim aginationT.h e commons inuouws aves hapee vi-
denti n mosta ll sourceos f studyo riginatesfr om Lissajousa,n d resulted
9:30 fromh ist ransfeor f tuningfo rkm otionsin toa pointo f reflecteldig htt hat
traverseda screenL. issajoupse rformedh is experimentwsi th finelyf o-
B7. Quasiperiodo f variationsi n the backscatteringan d total cross cusede lectricla mpl ight,t uningf orks,a ndm irrorsS. imilare xperiments
sectionos f sphericasl hellsS. tevenG . Kargl and PhilipL . Marston canb er eplicatetdo dayu singla serli ghta nda udios peakerTsh. uso nec an
(Departmenot f PhysicsW, ashingtonS tateU niversityP, ullman,W A morer eadilyg aina na ppreciatiofno r thef amiliarw avep atternr epresent-
99164-2814) ing sound,a nd seeb y the simplei nstrumentsu sedt o createi t, how this
waveformis n ota trued epictiono f thes hapeo f soundw avesin a medium.
Quantitativrea ym ethodfso r leakys urfaceel asticw avesa rea pplied
It isi n realitya displacemevnet rsutsim eg raphB. yu singm ultiplefo rkso r
[P. L. MarstonJ,. AcoustS. ocA. m.8 3,2 5-37( 1988)]t o approximate
speakerisn opposinpgl anesa ndt unedt o variousfr equencietsh, ec reation
theq uasiperioodf s tructureins backscatterianngd t otals catterincgr oss
of the singlea- ndm ultiple-ellipsLeis sajoupsa tternsth at are oftenp ro-
sectionsT.h e relevanat mplitudeisn thism odecl ontaina Fabry-Perot
ducedo n an oscilloscopsec reenc an alsob e accomplished.
resonancdee nominatowr, hich for spheresis [1 +exp( 2tr/3(cid:127)
+ t2rac/c(cid:127)) ] for the lth classo f SEW;x = ka = (cid:127)oa/c andc (cid:127) (x) and
/3,( x) aret heS EWp hasev elocitayn dr adiationd ampincgo e(cid:127)cient.T he
incremenint x betweerne sonancfeosra givenl followfsr omt hec ondition
A(xc/c(cid:127)) = 1. From the Taylor expansion[c ,(x+ Ax)]-(cid:127)
(cid:127)c(cid:127)(x) (cid:127) + Axd(c(cid:127) (cid:127))/dx, the approximatree sonancsep acing
Ax(cid:127)c(cid:127),/c forw eakldyi spersiSvEeW h avinag g roupve locitcy(cid:127) ( x) is 10:15
obtained(.T hisa pproximatiohna sb eenn otedb yo thers.T) heq uasiper-
B10. Acoustic surface shape resonances. Alexei A. Maradudin
iodo fa b roads tructurinet het otals catterincgro ssse ctioinsa lsoa pproxi-
(Departmento f PhysicsU, niversityo f California,I rvine,C A 92717)
mateda sA x(cid:127) (cid:127) 2(cid:127)r [ 2 cos0 , - (c/c,)( (cid:127)r - 20(cid:127) ) ] (cid:127), sin0 , = c/c,,w hen
dispersioisnn eglecteTdh. isf ollowsfr oma conditioonn t hep hasien cre- Acoustics urfaces haper esonanceasr ev ibrationael xcitationsth at are
mento f the forwarda mplitudeB. oth typeso f variationsd uet o Lamb localizedin thev icinityo f an isolatedp rotuberancoer indentationo n the
wavec ontributioncsa nb es eenin exacta ndr ay-synthescisa lculationfso r otherwisep lanar,s tress-freseu rfaceo f a semi-infinitee lasticm edium.T he
a sphericasl hell. [Work supportedb y ONR. ] protuberancem ay be fabricatedf rom the samem aterial as the substrate,
or froma differenmt aterialI.n generalt,h erei sa n infiniten umbero f such
resonanceass sociatewdi th a givens urfacep erturbationT.h eir frequen-
ciesa red iscretbee causoef thel osso f translationsayl mmetrcya usedb y
thes urfacpee rturbatiotnh;e ya rec omplebxe causteh eyo verlapth er ange
of frequencieasll owedt hev ibrationso f thes ubstratein, tow hicht heyc an
9:45
decaya; ndt heyd ependo n thes hapeo f the protuberancoer indentation,
B8. New rigorous and ray-acoustict raveling wave formulations for ando n the relationo f the materialp ropertieos f the protuberanc(em ass
source-excited thin elastic spherical shells immersed in fluids. L. density,e lasticm oduli) to thoseo f the substrateM. ethodsf or calculating
B. Felsena ndJ . M. Ho (Departmenot f ElectricaEl ngineerinagn d the frequencieosf the acoustics urfaces haper esonanceass sociatewdi th
ComputeSr cienceP, olytechniUcn iversityF, armingdaleN, Y 11735) protuberanceosr indentationos f simplef ormsa re describedR. esultsa re
presentetdh ats uggestht ata coustiscu rfaces hapere sonancecsa nb es tud-
A continuouLse gendr6tr ansforms panningth e polara ngle( 0) do- iede xperimentallbyy thes catteringo f acousticw avesfr om thes tructure
main - o(cid:127) < (cid:127)9< o(cid:127) is employedto derivea rigorousn ewi ntegrarl epre- supportingt hem.
S5 J.A cousSt.o cA. mS. opp1I., V ol@. 6F, all1 909 118thM eetinAg:c ousticSaolc ietoyf A merica $5
10:30 11:15
Bll. Diffractiono fa points ourcea bouta disk.J .J. Dlubac,C .W. Jiang, B14. Predictiono f bendingr esonanceosn elastics pheroidsd uet o oblique
and B. Yim (David Taylor ResearchC enter, Bethesda,M D 20084- incidenpt lanew avesfr ome xactb eamt heorya ndc omparisoton T-matrix
5000) calculationsM. . F. Werby (NORDA, NumericalM odeling,S tennis
SpacCe enterM, S 39529)a ndG . C. Gaunaurd(N avalS urfacWe arfare
Computationosf diffractiono f an acoustipc oints ourcea bouta hard Center,W hite Oak Laboratory,S ilver Spring,M D 20903)
ands oftd iska rep resentedT.h es olutiong, ivena sa serieso f oblates pher-
oidalw avefunctionsis,b asedo nt hec lassicaaln alysis[ J . J. BowmanT, . B. Exactb eamt heoryp redicttsh ep resencoef bending or flexurarle -
A. Senior,a ndP . L. E. UslenghiE, lectromagnetaicn d,qcoustiScc attering sonancefrso mo bliquein cidenpt lanew avesI.n an earlierp aperT, imo-
by$ impleS hapes(N orth-Holland,A msterdamT, he Netherlands1, 969), shenkoth eory,w hicha ssumeas constanmt omento f inertiaa longt he
Chap. 14]. In the limit as the sourceg oest o infinity,t he plane-wave beam,w ase mployedto derivea n approximatteh eoryt o predicftl exural
solutionis r ecoveredC. omputationws ith thef ieldp ointo n thed iskv erify resonanceGso. oda greemenwta sf ound( for thel owerm odesw) ith the
the boundaryc onditions.P arameters tudiesa re presenteda, nd conver- exact T-matrix calculationsb asedo n exact3 -D elastodynamicsIt. is pos-
gencec riteria are discussed. siblet os olveth ee xactb eame quationu singp hasem atchingte chniquetos
predictb ending resonancleo cationsS. uchc alculationasr ep erformed
for spheroidfso r aspecrta tiosf rom 1.5t o 10,w ithe xtremelyg ooda gree-
mentb etweenb eamt heorya nd the exact T-matrixc alculationfso r all
modes.
10:45
B12. Reflectivity of monolayerso f bubblelikes catterersa t water/solid 11:30
interfacesI.v an Tolstoy (KnockvennicC, astleD ouglasD G7 3PA, SW
Scotland) B15. Sounds catteringf rom a submergedfi nite cylinderw ith ribs. Philip
J. Moser,J ian-RenY uan, and Herber(cid:127)bt erall (Departmenot f
By redistributingth e energyf lux of an incidentp lanew ave,a toorio- PhysicsC, atholicU niversityo f America,W ashingtonD, C 20064)
layero f identicalb ubblelikes catterersa t an interfacem ay, at frequencies
closet o the monopolcre sonancteo t,d, rasticallya ltert he reflectivityo f the The effectso f an almost-periodicallsyp aceds eto f ribso n the scatter-
surfaceR. eflectivitcya lculationasrc g ivenf or a wavei ncidennt ormally ing of soundf rom a submergecdy lindero f finitel engtha rei nvestigated.
uponi nfinites quarela ttices( of basisl) for threem odels(: 1) air bubbles The cylinderi s eithera ssumedso ft( correspondintgo a veryt hin air-filled
in a liquidf ullspac(e2,) ' airb ubbleast a water/harsdu rfacoer water/ shell)o r rigid (correspondintog a heavyt hicks hell),a ndi ts scattering
elasticp latei nterfacea, nd (3) air-filledc avitiesin a rubberl ayera t such amplitudeis o btainedu singth eg eometricathl eoryo f diffractionT.h e rib
an interface.T hesei llustratet he essentiarlo le of multiple scattera nd, scatterinagm plitudeis f oundf romc urvaturec orrectedre sultso f thet heo-
mosti nterestinglyt,h ep ossibilityo f reflectivityn ullsf or incidentf requen- ry for a flat platec arryinga rib. Numericalr esultsa res hownf or thec ase
ciest o-(cid:127)too-F or case( 3), useo f rubberc onstantgsi venb y earlierw riters of softc ylinderst;h eye xhibitt he onseta nd emergencoe f rib effectso ver
[Gaunaurde tal., J. Acoust.S oc.A m. 65, 573-594 (1979) ] showsth at it the backgrounodf scatteringfr om the bodyo f the cylinder.
is theoreticallpy ossiblteo selecvt alueso f kl sucht hat a hardw all (or an
elasticp late) becomesfu lly anechoicfo r given to(cid:127)-too. For the rubber
typesc onsideredth, ee ffectivbe andwidtho f thise ffect( 99% anechoicity)
,xco/coo v ariesb etween0 .01 and0 .05. [Work supportedb y ONR.] 11:45
B16. Diffraction tomographiei nterferometry, a new imaging technique.
Woon S. Gan (Acoustical ServicesP te Ltd., 29 Telok Ayer Street,
Singapore0 104, Republico f Singapore)
A new imagingt echniqued, iffractiont omographicin terferometry
11:00 (DTI), is proposedD. ouble-exposurDeT I and time-averageDd TI are
consideredT.h e Borna pproximationis usedt o obtaint he scatteredw ave
B13. Acoustical imageso f a submergeda luminum sphere. Char]cs
and the filtered-backpropagataiolgno rithmi n the reconstructionF.o r
F. Gaumond,B rian H. Houston( Codes5 132a nd 5136,N aval Research
double-exposuDrTeI , summatioonf t het wot omogramgsi vesth ed iffrac-
Laboratory,W ashingtonD, C 20375-5000),a nd SheilaW oo (Sachs
tion tomographiicn terferogramR.e constructiogniv esa cross-sectional
Freeman Associates,L andover, MD 20785)
imagec overedw ith interferencfer ingesF. or time-averageDdT I, the in-
Acousticailm agesu singr eflectionto mography[P . B. Abrahama nd tensityo f ther econstructeimd agei se xpresseidn termso f thec haracteris-
C. F. Gaumond, J. Acoust. Soc. Am. 82, 1303-1314 (1987)] wcrc made tic function.T his givesa cross-sectioncaol ntouredim ageo f the object
from 3-D acousticasl catteringd ata. The data were taken from a 7.6-cm modulatedb y a systemo f interferencefr inges.F or the proposede xperi-
(3.0-in.) solida luminums phereu singa semicirculahr oopa rray with mentals etupf or thed ouble-exposuDrTe I, thei nterferogramof theo b-
radius0 .85 m, which rotateda round the sphere.T he clements pacingi n ject,a turbineb ladei n its unstressesdta tea nds tressesdt ate,i s recorded
the hoopw as2 ø .T he hoopw asr otatedi n 2ø i ncrementfsro mt he back- with the objecti lluminatedf rom variousd irectionsF. or the proposed
scatteredd irectiont o the forwardd irection.T he frequencyr angeo f the experimentasle tupfo r thet ime-averageDdT I, a diffractionto mogramis
data was 2.7-25 kHz. Thesea cousticailm agesw ere comparedw ith ana- exposefdo r a periodo f timeb y rotatingt he illuminatings ourcea round
lytically produceda cousticailm ages. the objects everatl imes,d uringw hich the objecte xecutesa motion.
S6 J. Acoust.S oc. Am. Suppl.1 , Vol. 86, Fall 1989 118thM eeting:A cousticaSl ocietyo f America S6
TUESDAY MORNING, 28 NOVEMBER 1989 ST. LOUIS BALLROOM H, 8:00A .M. TO 12:15P .M.
Session C. Underwater Acoustics I: Acoustic Fields
John Perkins, Chairman
Code5 160,N avalR esearchL aboratoryW, ashingtonD,C 20375
Chairman's Introduction--8:00
ContributedP apers
8:05 Can matchedf ield processinbge usedt o determinet he sound-speed
environmentg ivena knowns ource?R ecentc omputationsa re very prom-
CI. Three-dimensionaml atched-fieldp rocessingw ith an eigenvalue isingi n spiteo f expectedd ifficultiesr elatingt o the nonuniquenesosf solu-
methodM. ichaelD . Collins,W . A. Kuperman,J ohnS . Perkins,L aurie tions.I n the range-independencta se,t he essencoe f the approachis to find
E. Tinker (Naval ResearchL aboratory,W ashingtonD, C 20375), and the sound-speepdr ofilet hat will maximizet he powers eena t the array.
John Glattetre (NorwegianD efenseR esearchE stablishmenPt, .O. Box Thish asr esultedin a profilet hati sc lose to thet ruep rofilea ndf oundb y
115, N-3191 Hotten, Norway) meanso f an exhaustivsee archo f the parametesr paced escribintgh ef am-
ily of potentiapl rofilesT. he parametesr pacec onsistosf thec oefficienotsf
An eigenvalume ethodf or three-dimensionmala tched-fielpdr ocess-
the major empiricalo rthogonalf unctions( EOFs) computedf rom the
ing with a verticala rrayh asb eend evelopedfo r localizationo f multiple
covariancme atrixo f sound-speepdr ofiles amplesS. ubsurfaceosf the pa-
sourcesin rangea nd depth (bearingc an also be determinedw ith the
rameter spacea re easily plotted and show well-defined,i nformative
methodif thee nvironmenista symmetricT).h em ethodin volveasp plying
trendsU. nfortunatelyit, erativete chniqueisn vestigatesdo f ar haves hown
the Bartlettb eamformetro the eigenvectorosf the cross-spectrdael nsity
convergencdei fficultiesin that they findl ocalm aximaw hichc orrespond
matrix. This approacha ppearst o be more effectivet han the standard
to profilesw hich are not closet o the true profile.R esultsw ill showt he
eigenvaluea pproachin volvingb eamformingo n a linearc ombinationo f
procedures ensitivitya sa functiono f arrayl ength,s ourcer ange,d epth,
severael igenvectorsE.i genvalueb eamformingm ethodsa re basedo n the
andf requencyT.h e keyt o succesfso r thet echniquies thec omputatioonf
orthogonatla rgetsa pproximation[R . F. Oragg,N RL Rep. 9143, Naval
good EOFs.
ResearchL aboratoryW, ashingtonD, C (1989) l- The spatiacl orrelation
over a horizontala rray of two sourcesis small providedt he sourcesa re
sufficientlys eparatedin bearing.O n the other hand,t he spatialc orrela-
tiono vera verticala rrayo f two points ourcems ayb e relativelyla rgef or
somes ourcel ocations( i.e., the Bartlett matched-fieldp rocessofro r a
8:50
verticala rrayh asr elativelyla rges idelobes)H. owever,s imulationssu g-
gestt hat thise ffectd oesn ot seriouslyd egradet he eigenvaluep rocessing C4. Low-frequencya coustict omographyu singm atchedf ield processing.
methodf or verticala rrays.S ourcem otionw ill furthere nhanceth isp ro- II. A. Tolstoy (Code 5120, Naval ResearchL aboratoryW ashington,
cessingm ethod. DC 20375)
Part I discussetdh e difficultiesa nd successeosf the MFP techniquein
a range-independeenntv ironmenPt.a rt II discussepsro grestso d ata( sim-
ulationso nly) concerninag range-dependeendtd ye nvironmentF. irst,a
8:20 sound-speesdtr uctureis computeda s the sumo f two Gaussiane ddys.
Next samples ound-speepdro filesa re computeda longa selectedra dial
C2. A perturbationm ethodf or normalm odet heoryw ith variablev elocity and used to calculate the basic EOFs for the entire environment. The
profile. M. F. Werby (Schoolo f Physicsa nd Astronomy,U niversityo f EOFs themselveasr e fairly insensitiveto how the samplingi s donea l-
MinnesotaM, inneapolisM, N 55455a ndN ORDA, NumericaMl odeling thought heirc oefficienctsa nc hanges ignificantlyG.i vena seto f EOFs,
StennisS paceC enter,M S 39529},a ndP aul Ellis (Schoool f Physicsa nd plotso f theirc oefficienatss a functiono f rangea ndc rossra nges howw ell-
AstronomyU, niversityo f Minnesota,M inneapolisM, N 55455) definede, asilyin terpolatebde haviorM. oreovero, nlyt woE OFsa ren eed-
ed to describea sound-speepdr ofilet o a highd egreeo f accuracyR. esults
Normalm odet heoryi sa veryw ell-developetde chniquefo r predicting
will be presenteedx aminingth e sensitivitoy f MFP to changesin the
the propagationlo ssi n the oceanf or most stratifiede nvironmentsa nd
coefficientsR. egionso f high sensitivityr equiref requentp rofilee stima-
velocityp rofilesa, s well as somer ange-dependenent vironmentsS. o why
tionsa nd increaseden vironmentasla mplingP. rogressto date suggests
another method? The reason is that sometimes it is desirable to retain the
that the largef amilyo f parametevr alues( at leastt wo parametersi.,e .,
simplet rigonometricfu nctionso btainedf rom constantv elocityp rofiles.
EOF coefficientsp,e r profile) plus iteratived ifficultiesa s seeni n Part I
This is usuallyd oneb y employingth ea pproximates chemeo f usingm ulti-
mayr equiret hea pplicationo f computationalliyn tensivtee chniquessu ch
ple layersi n eacho fwhich the velocityp rofilei s assumedco nstantI.n this
as simulateda nnealing.
work, it is shownt hat this can be carriedo ut nicelyb y representingth e
velocity profile in terms of a mini-max fil usingT schebyschefpf olynomi-
alsa nd a first-orderp erturbationt echniqued erivedf rom Sturm-Liouville
theory.T he derivationle adst o a compactc losede xpressiotnh at is easily
programmableT.h e resultsfr omt hef ormulationa rec omparedw ith other
methods. 9:05
C5. Environmental mismatehinge ffectso n sourcel ocalization processing
in mode space. E. C. Shang and Y. Y. Wang {CIRES, University of
Colorado/NOAA, Wave PropagationL aboratory, Boulder, CO 80303)
8:35 The performanced egradationo f the matchedf ieldp rocessing(M FP)
causedb y environmentaml ismatchingh asb eena n intriguings ubjectA.
C3. Low-frequencayc ousticto mographuys ingm atchedfi eldp rocessing. greatd ealo f studyh asb eend oneb y numericasl imulationsI.n thisp aper,
I. A. Tolstoy( Code 5120, Naval ResearchL aboratoryW, ashington, this problemi s studieda nalytically.A nalytic investigationis important
DC 20375) becauseit revealss omeo f the physicailn sightsa nd providesg uidelinesfo r
S7 J. Acoust. Soc. Am. Suppl. 1, Vol. 86, Fall 1989 118th Meeting:A cousticaSl ocietyo f America S7
9:50
a self-coherent scheme[ H. Bucker,J . Acoust.S oc.A m. Suppl.1 84,
S19 (1988) ]. It hasb eeni llustratedth at the sourcera ngei nformationis
C8. Effect of internal soiltonso n shallow-waters oundp ropagation.J i-
associatewdi th them odalp hased ifferencaen dt hes ourced epthi nforma-
xun Zhou,X ue-zhenZ hang,a ndP eter Rogers( Schoool f Mechanical
tion isa ssociatewd ith them odala mplituder atio whenM FP is performed
EngineeringG, eorgiaI nstituteo f TechnologyA, tlanta,G A 30332)
in modes paceT. herefore,t he modalw avenumbepr laysa key role in
sourcel ocalization.M ismatchinge ffectsc an be investigateda nalytically
Thereh aveb eenm anyr eportso n observationosf naturallyo ccurring
by takinga dvantageo f calculatingth em odalw avenumbeerr rorb y modal
internals olitaryw avetrains(s oiltons)i n the coastz one,e specialliyn the
perturbationth eory.[ Work supportedb y NOAA and NOSC.]
summerT. he mechanismfo r the generationo f thesen onlinearin ternal
wavesh asb eeni nvestigateidn the geophysicasn d fluidm echaniccso m-
munity. Little attention,h owever,h as beenf ocusedo n their effecto n
soundp ropagationw ith the exceptiono f the work of Baxter and Orr,
which was basedo n ray theory [L. Baxter and M. H. Orr, J. Acoust. Soc.
Am. 71, 61-66 ( 1982) ]. In thisp aper,t hep arabolice quation( PE) model
9:20
(IFD or PAREQ code)i s usedt o numericallys imulatet hee ffecto f inter-
nal solitonso n low-frequencsyo undp ropagationin the coastz one.T he
C6. Nonlinear biaso f travel time in modalo ceana coustict omography.E .
resultss howt hat soundt ransmissionlo ssi s sensitiveto solironp arameters
C. Shang( CIRES, Universityo f Colorado/NOAA, WaveP ropagation
(sucha sw avelengtha,m plitudee, tc.) andw avep acketp arameter(s p osi-
Laboratory,B oulder,C O 80303)
tion, number,a nd propagationd irection).T he resultsc an be usedt o ex-
plain,a t leastp artly,a n interestinegx perimenpt henomenaT:h e frequen-
In a previousp aper[ E. C. ShangJ, . AcoustS. oc.A m. 85, 1531-1537
cy responsoe f shallow-watesr oundp ropagationu ndert he conditiono f a
(1989) ], oceana coustitco mographbya sedo n thea diabaticn ormalm ode
thermoclined uring the summeri s often a strongf unctiono f spacea nd
theoryh asb eend evelopedM. esoscalset ructurec anb ei nvertedb y usinga
time,a nd soundp ropagationo verc ertainf requencyra ngesh asa n abnor-
linearr elationshicpo nnectintgh em odalt ravelt imep erturbationan dt he
mal attenuationth at cannotb ee xplainedb y usingc onventionaml odelso f
sound-speepde rturbationT. his linearr elationshipis only an approxima-
soundp ropagation[.W ork supportedb y ONR. ]
tion duet o the followingt wo facts:( 1) neglectingth e differenceb etween
perturbedm odale igenfunctioann dt heb ackgroundm odele igenfunction;
(2) takingth ef irst-ordeerx pansioonft hep otentiafl unctionA K: (z,r)
to calculatet he modalw avenumbepr erturbationC. omparingw ith ray
10:05
tomographyit,e m(1 ) is thet ermc orrespondintgo ther ay pathp erturba-
tion. It has beenf ound that item (1) is not significanta nd the problem
C9. Measurement of shallow-water sound transmission on the New
causedb y item (2) can be recoveredb y a post-correction procedure
Jersey continental shelf. Lynne Maiocco, William Carey (Naval
proposedin thisp aper.[ Work supportedb y NOAA and ONR.]
UnderwaterS ystemCs enter,N ew London,C T 06320), Edwin Parssinen
(Kildare Corporation,9 5 Trumbull Street,S uite D, New London,C T
06320),and James Doutt (WoodsHoleOceanographicInstituteW, oods
Hole, MA 02543)
Calibrated acoustic transmission measurements were made on the
9:35
New Jerseyc ontinentasl helfi n the vicinityo f the AMCOR 6010 bore-
hole,a n areaw ith knowng eophysicaplr opertiesT. he waterd epthw as7 0
C7. The normal mode theory with bottom elasticity and range
m andt he experimenwt asc onductedu nderk nowno ceanographcico ndi-
dependenceJ.u anI . Arvelo (Code U25, Naval SurfaceW arfare Center,
tionsa ss hownb y measurementosf salinity,t emperaturea, nd sounds peed
10901N ew HampshireA venue,S ilver Spring,M D 20903-5000)a nd
versusd epth.T he acousticm easuremenwtse rep erformedw ith a vertical
Herber0t befall (Departmenotf PhysicsC, atholicU niversitoyf
arrayo f 24 equallys pacedh ydrophoneos,n eo f whichw aso n theb ottom.
America, Washington,D C 20064)
A calibrateds ourcew asu sedt o obtaint ransmissiolno ssd atat o rangeso f
26 km at discretef requenciesfr om 50 to 600 Hz. The data from three
The theoryo f normalm odesh asb eene xtendedt o accommodatteh e
hydrophonews erep rocessefdo r a 4-km rangeu singt echniquedse veloped
effectso f shearw avesi n the elastico ceanf loor. The effecto f absorption
by Frisk and Lynch [J. Acoust.S oc.A m. 76, 205-216 (1984)] to yield
has alsob eeni ncludeda s the imaginaryc omponenot f the sheara nd
wavenumbesr pectraT. he transmissiorne sultso f threeh ydrophoneast 50
compressionawla venumbersA. semi-infinitee lasticb ottomb asement
layer hasb eeni ncludeda nd it was foundt hat the absorptionc ausesth e Hz weref oundt o havea n interferencep atternc learlyr esultingfr om two
modesL. ow-frequencdy ata (20 to 50 Hz) wereo btaineda t discretelo ca-
wavenumbers pectrumo f the radiatingm odest o be inherentlyd iscrete,
tionsf rom the buoyt o yieldv alueso f normalb oundaryi mpedanceT. rans-
hence,t he numbero f radiatingm odesis drasticallyr educedr elativet o the
oneso btainedw ith the deepf alseb oundaryT. he ranged ependencoef the missionlo ssd ataw ereo btaineda t eightf requencies5,0 to 600 Hz, alonga
constandt eptha ndg raduallyc hangingd epthr adial.T he constandt epth
acousticp ropertiesa nd of the boundarieso f the oceanh asb eeni ncluded
by a modifiedv ersiono f the adiabaticn ormal mode theory. Comparisons radial resultsw erec omparedt o calculationsp erformedw ith IFD-PE and
SAFARI usinga geoacoustimc odelb asedo n measuredg eophysicapl rop-
are made with experimentaml easurementosf the transmissionlo sso f
erties.P redicteda nd measuredl evelsg enerallya greed,h owever,d iffer-
underwatere xplosivesa nd with resultsf rom Collins' HEPE mode.
[Work supportedb y the IndependenRt esearchB oardo f the Naval Sur- encesin thec omputeda nd them easuredm odali nterferencpe atternsw ere
observed.
faceW arfare Center and by NORDA. ]
10:20-10:30
Break
10:30
This paperw ill describeth e resultso f a models calee xperimenot n
soundp ropagationin a penetrablteh ree-dimensionwale dgew ith a fluid
bottom. The wedgem odel is 1.2X2.4 m and has a Mylar-kevlar mem-
C10. Experimental results of sound propagationi n a penetrable wedge
branet hat separatestw o fluids (water and ethyleneg ylcol) with sound
with a fl.uidb ottom. Stewart A. L. Glegg and Ian House (Center for
speedso f 1500m /s alad1 700m /s. The modeli s suspendeidn a largew ater
Acousticsa nd Vibration, Department of Ocean Engineering,F lorida
tank so that reflectionsfr om the edgeso f the model are not significant.
Atlantic University, Boca Raton, FL 33431)
S8 J. AcoustS. oc.A m.S uppl.1 , Vol.8 6, Fall1 989 118thM eetingA: cousticaSlo cietyo f America $8
Thee xperimenhta sc oncentrateodn acrosssl opep ropagatioant several modes pacem atched-fieldte chniquems orea pplicableto actualp hysical
differendt ownslopraen gesu,s inga high-frequenpcuyl seT. hep ulses pec- environment[sT . C. Yang,J . AcoustS. oc.A m. 82, 1736-1745( 1987}] .
tra haveb eenc omparewd ith Buckinghamt'hs eoreticaml odelf or sound A fresha pproachis broughtt o thisp roblemh ereu singc omputers imula-
propagatioinn a penetrablwe edge.[ Work supportedb y ONR.] tionso f matched-fieldp rocessinign a Pekerisw aveguideto demonstratae
new methodf or extractingm odala mplitudesfr om data.T heses imula-
tionsd emonstratteh at thisn ewm ethodo f modala mplitudee xtraction
allowss uccessfuml odes pacem atched-fieldde tectiona ndl ocalizationa t
array aperturess ignificantlys mallert han thosea llowedb y previously
10:45
useda lgorithmsF. inally,t he algorithmw ill be discusseidn the general
C11. The resolutiono f modal Doppler shifts in an acousticw aveguide. contexto f dimensionarle ductionte chniques.
Hee Chun Song and Arthur B. Baggeroer( Department of Ocean
EngineeringM, assachusettIsn stitute of TechnologyC, ambridge,M A
02139)
A methodf or estimatingth e sourc(cid:127) velocityf rom the acoustics ignal
11:30
fieldp ropagatinign a dispersivoec eanicw aveguidies presentedT.h e sig-
nal is observeda t an omnidirectionarle ceiverin the presencoe f additive C14. Combinedo ceanographica nd acousticm odeling.M ichael Porter,
whiten oiseT. he sourcetr ansmitsa continuous-wav(ec w) signala, ndt he Steve Piacsek, Laurel Henderson, and Finn Jensen (SACLANT
source motion is assumedt o be uniform (unaccelerated). The ocean is Undersea,R esearchC entre, I-19026 La Spezia,I taly)
modeleda s a waveguideth at is horizontallys tratifiedw ith an arbitrary
An importantc lasso f oceanographmic odelsis them ixedl ayerm odels
sound-speepdro filei n thev erticalT. he acoustifci eldg eneratebdy a mov-
that, simplys tated,p rovidedp redictionso f mixedl ayer deptha nd tem-
ing points ourcein termso f normalm odesp redictst hat eachm odeh asa
peratureT. hesep redictionsta kei nto accountt hes urfacew indst hat drive
differentD opplers hift, whichc ontrastsw ith a singleD opplers hift in a
the mixinga nd the solarr adiationt hat heatst he mixedl ayer.A s interest
homogeneouusn boundedm edium.T he modesa re consideredto remain
has increasedin usings uchm odelsa s a stepi n the processfo r making
phaselo ckedw ith eacho ther,i .e., coherentT. he sourcev elocity,i nclud-
acousticfo recastos r nowcastsa, recurringq uestionh asb eent hat of what
ing the numbero f modesi nvolved,c an be estimatedt hroughr esolving
informationi s neededf or accuratea cousticp redictionsF. or instanceh, ow
Dopplers hifts.T he methodi s a time-domainin terpretationo f a recently
preciselyd o mixed layer depthsn eed to be calculated?! s mixed layer
developede igcnstructurtee chniquef or multitargetd irectionf indingw ith
temperatureim portant?T hesea ndo therq uestionasr ea ddressetdh rough
passivea ntenna arrays, in conjunctionw ith smoothingp reproecssing
a parameters tudyu sings ynthetics ound-speepdr ofilesa s input to an
schemet o deal with coherentm odes[ Shan et aL, IEEE Trans. Acoust.
acousticm odel.T he implicationasr ed emonstrateidn a somewhamt ore
SpeechS ignalP rocessA. SSP-33 (4) (1985)]. Simulationr esultst hat
concretefo rmi n a two-stepp rocessT:h e SSPi sp redictedu singp articular
illustratet he performanceo f the methoda re presented.
mixedl ayerm odels( Niiler, Mellor-YamadaG, arwoode, tc.) andp assed
toa na coustimc odelt o providetr ansmissiolons sc alculationsT.h e results
are alsoc omparedt o predictionsb asedo n both measureda nd historical
SSP measurements.
11:00
c12. Impulse responsef or propagation in the ocean sound channel.
StanleyM . Flattr, John Colpsi,T imothyF . Duda, Galina Rovner,a nd
Jan Martin (PhysicsD epartmentU, niversityo f California,S antaC ruz,
CA 95064) 11:45
Usingt he SDSC/CRAY and the parabolice quationp, ulsep ropaga- C15. The transportc oherenceo f acousticf ields as a criterion for range
tion wass imulatedi n the oceans oundc hannel.P ulsesw ith 200 frequen- dependencein an ocean channel. B. G. Hurdle (Naval Research
ciesb etween1 0 and 50 Hz weres ynthesizedg,i vinga pulsew idtho f ap- LaboratoryC, ode5 103, WashingtonD, C 20375)
proximately2 5 ms, and a pulser epetitiont ime of 5 s. The wave fronts
createdb y thist echniquhea vea simplea ndi ntuitivec haracteru, nliket he A paperw as presentedlB . Hurdle, J. Acoust.S oc. Am. 55, 452
fieldsf or singlef requenciesP. ictureso f wave frontso ut to 1000k m, and (1974) ] on the natureo f acousticin terferencefi eldsi n a geometricd isper-
possiblay moview, ill bes hownW. avef rontr econstructiobny meanso f a siveo ceanc hannel.T he structurea nd multiplec omponentos f the fieldsa s
muchf asterc alculationi n termso f ray theoryw ill be demonstratedT. he a functiono f the velocityo f the source,t he geometryo f the boundaries,
effects of internal waves on the wave fronts will be described in terms of andt he sound-speesdtr uctureo f thec hannewl ered iscusseTdh. is paper
wavef rontc orrugationsa,n dt he useo f impulsem easuremenotsv erv erti- reviews the nature of the fields and, based on the field characteristics,
cal arrays to measuret he propertieso f the internal-wavef ield will be providesa criterionf or determiningth e degreeo f ranged ependencoef an
discussed[.W ork supportedb y ONR, Code 1125OA.] oceanc hannel.T his criterioni s basedo n the transportc oherenceo f the
field and is measured in terms of the correlation coefficient of the trans-
portedf ielda sa functiono f thes eparationd istanceb etweentw o receivers
ast he fieldi s transportedth ed istanceb etweenth em.T he differencein the
transporct oherencaen dt hec oherencien thef ieldf or beamf ormingw ill
11:15 be discussedS. omeo ther applicationso f this conceptw ill also be dis-
cussed.
C13. Modal matched-fieldp rocessinwg ith smalla (cid:127)rture verticala rrays.
G. B. Smith, G. M. Frichter, IV (Naval Ocean Research and
DevelopmenAt ctivily, Code 244, StennisS paceC enter, MS 3952%
5004), C. Feuillade( SyntekE ngineeringan d ComputerS ystemsI,n c.,
2101 East JeffersonS treet, Rockville, MD 20852), and C. L. Byrne
(Departmenot f MathematiesU, niversityo f Lowell,L owell,M A 01854)
12:00
In the past years, much attention has been given to mode space
C16. The use of neural networks in acoustic coherence measurements.
matched-fielpdr ocessinign shallow-watelro, w-frequenceyn vironments.
Mark J. Beran (Department of Electrical Engineering, Catholic
In thist ypeo f situationm, odes pacem atched-fielpdr ocessinhga ss everal
Universityo f America,W ashingtonD, C 20064)
advantageosv er conventionaml atched-fieldp rocessinsgu cha s: lower
procc(cid:127)ing dimension, better sidelobe rejection, and the ability to dis- The tntensity dlstnhuuon of an incoherent target may he determined
criminates ignala gainsmt odaln oiseH. owevere, xtractiono f modala m- from coherence measurements. It is shown here how a neural network
plitudesfr om datab y the methodp ioneeredb y Shang[ J. AcoustS. oc. may be developedto solvet his inversep roblemT. he effecto f random
Am. 77, 1413-I 418 (1985) ] is not veryr eliablef or smalla perturea rrays. phasev ariationsre sultingfr omo ceant emperaturfel uctuationiss c onsid-
Attemptsh aveb eenm adet o overcometh is problemin ordert o make ered in the formulation.
S9 d. Acoust.S oc. Am. Suppl. 1, Vol. 86, Fall 1989 118th Meeting:A cousticaSl ocietyo f America S9