impacts of environment-dependent acoustic propagation on passive acoustic monitoring of ...

196 Pages·2017·6.48 MB·English

by  Carolyn Binder

IMPACTS OF ENVIRONMENT-DEPENDENT ACOUSTIC
PROPAGATION ON PASSIVE ACOUSTIC MONITORING OF
CETACEANS
by
CarolynM.Binder
Submittedinpartialfulfillmentoftherequirements
forthedegreeofDoctorofPhilosophy
at
DalhousieUniversity
Halifax,NovaScotia
July2017
DRDC-RDDC-2017-P060
(cid:2)c HerMajestytheQueeninRightofCanada,MinisterofNationalDefence,2017
For my family. I couldn’t have done this without your support, dedication,
and love.
ii
T C
ABLE OF ONTENTS
ListofTables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
ListofFigures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv
ListofAbbreviationsandSymbolsUsed . . . . . . . . . . . . . . . . . . . . . . xv
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Chapter1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 LiteratureReview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 InvestigatingtheImpactsofEnvironment-DependentPropagationonan
AutomatedAuralClassifier . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1 ThesisOutline . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Chapter2 AutomatedAuralClassifierandPerformanceMetrics . . . . . 8
2.1 TheAuralClassifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.1 ValidationofClassifierPerformance . . . . . . . . . . . . . . . 10
2.2 PerformanceMetrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Chapter3 BiogenicandSyntheticVocalizationDataSet . . . . . . . . . . 18
3.1 BiogenicWhaleCalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 SyntheticWhaleCalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2.1 ComparisonofSyntheticCallswithBiogenicWhaleCalls . . . . 23
3.3 ConditioningandUpsamplingofSignalsforExperiments . . . . . . . . . 27
3.3.1 TimeSeriesforTransmission . . . . . . . . . . . . . . . . . . . 31
3.4 SignalDetection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Chapter4 PropagationExperiments . . . . . . . . . . . . . . . . . . . . . 33
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2 ExperimentalSet-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.1 AcousticRecordingEquipment . . . . . . . . . . . . . . . . . . 38
4.3 OceanEnvironmentMeasurements . . . . . . . . . . . . . . . . . . . . . 39
iv
4.3.1 WindSpeedandSurfaceRoughnessConditions . . . . . . . . . . 39
4.3.2 AmbientNoise . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.3.3 SedimentProperties . . . . . . . . . . . . . . . . . . . . . . . . 41
4.3.4 SoundSpeedProfiles . . . . . . . . . . . . . . . . . . . . . . . . 42
4.4 SourceLevelEstimates . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.4.1 Method1: TransmitSensitivityandTransducerInputVoltage . . 46
4.4.2 Method2: ReceivedSignalLevelonMonitorHydrophone . . . . 48
4.4.3 SourceLevelResultsandDiscussion . . . . . . . . . . . . . . . 50
4.5 ExperimentalResultsandDiscussion . . . . . . . . . . . . . . . . . . . . 53
4.5.1 ExampleDecisionRegions . . . . . . . . . . . . . . . . . . . . . 54
4.5.2 SummaryofPerformanceResults . . . . . . . . . . . . . . . . . 58
4.5.3 TrainingSetSelection . . . . . . . . . . . . . . . . . . . . . . . 64
4.6 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Chapter5 PulsePropagationModelling . . . . . . . . . . . . . . . . . . . 71
5.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.1.1 BroadbandModellingwithFourierSynthesis . . . . . . . . . . . 77
5.1.2 WaveformTransmissionThroughaChannel(WATTCH)Propaga-
tionModelandBellhop . . . . . . . . . . . . . . . . . . . . . . 79
5.2 SimulationofExperimentalConditions . . . . . . . . . . . . . . . . . . 85
5.2.1 EnvironmentandModelConfiguration . . . . . . . . . . . . . . 85
5.2.2 NoiseAddition . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.2.3 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . 91
5.3 SensitivitytoEnvironmentalParameters . . . . . . . . . . . . . . . . . . 95
5.3.1 EnvironmentandModelConfigurations . . . . . . . . . . . . . . 96
5.3.2 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . 97
5.4 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Chapter6 RelativeImpactofSNRandOtherPropagationEffects . . . . 103
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6.2 SeparatingContributionsofPropagation-InducedDistortionandSNR . . 105
6.2.1 Case1: AddingNoise . . . . . . . . . . . . . . . . . . . . . . . 106
6.2.2 Case2: AddingPropagationEffects . . . . . . . . . . . . . . . . 107
6.2.3 Case3: AddingNoiseandPropagationEffects . . . . . . . . . . 107
6.2.4 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . 107
6.3 IncreasedRangeResolution . . . . . . . . . . . . . . . . . . . . . . . . 111
6.3.1 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
6.3.2 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . 114
6.4 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
v
Chapter7 Impact of Environment-Dependent Propagation on Automatic
RecognitionofBowheadandHumpbackVocalizations . . . . . 121
7.1 EnvironmentandModelConfigurations . . . . . . . . . . . . . . . . . . 122
7.1.1 NoiseAddition . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
7.2 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
7.2.1 IsospeedEnvironment . . . . . . . . . . . . . . . . . . . . . . . 127
7.2.2 DownwardRefractingEnvironment . . . . . . . . . . . . . . . . 129
7.3 ChapterSummary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Chapter8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
AppendixA MooringDiagrams . . . . . . . . . . . . . . . . . . . . . . . . . 141
AppendixB DeterminationofHydrophoneDepthonSHARPMooring . . . 146
B.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
B.2 DeterminingHydrophoneDepthViaRayTheory . . . . . . . . . . . . . 148
B.2.1 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
B.2.2 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . 150
B.3 Determining Importance of Recorder Depth to the Aural Classifier Perfor-
mance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
B.3.1 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
B.3.2 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . 153
B.4 SummaryRemarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
AppendixC Temperature-SalinityDiagrams . . . . . . . . . . . . . . . . . 156
AppendixD ArrivalStructure . . . . . . . . . . . . . . . . . . . . . . . . . . 158
D.1 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
D.2 ResultsandDiscussion . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
AppendixE SelectionofSedimentParameters . . . . . . . . . . . . . . . . 164
E.1 Impact of Sediment Density on Propagation Effects and Classifier Perfor-
mance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
E.2 SummaryRemarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
vi
L T
IST OF ABLES
3.1 Frequencyrangeanddurationofwhalevocalizationsinthebiogenic
dataset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.2 The five features that best discriminated between bowhead and
humpbackwhalecalls. . . . . . . . . . . . . . . . . . . . . . . . . 25
4.1 Depths of hydrophones deployed during both days of the Gulf of
Mexicoseatrial. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2 Transmission ranges of signals during the Gulf of Mexico experi-
ment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3 Samplingformatsforacousticrecordingpackages. . . . . . . . . . 39
4.4 Transmission loss values used for estimating the source level of
transmittedsignals. . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.5 Estimatedsourceleveloftransmittedsignals. . . . . . . . . . . . . 52
4.6 Numberofdetectionsandclassifierperformanceforbiogenicbow-
headandhumpbackcallsrecordedbytheicListenonmooring4. . . 54
4.7 Numberofdetectionsandclassifierperformanceforsyntheticbow-
head and humpback calls recorded by the icListen on mooring 4.
Nouncertaintyestimatesareprovidedhere fortheclassifierperfor-
manceresultsbecausek-foldcross-validationwasnotimplemented. 57
5.1 Summary of the main considerations when selecting a numerical
techniqueforoceanacousticpulsepropagationmodelling. . . . . . 76
5.2 RangesoverwhichsignalswerepropagatedthroughtheWATTCH
modelforeachofthereceiverdepths. . . . . . . . . . . . . . . . . 87
5.3 Example performance values for signals propagated through the
WATTCHmodelover6.5kmthroughthedownwardrefractingenvi-
ronment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
B.1 ComparisonofexperimentalandBellhop-modelledtimedifferences
betweenthedirectarrival,andsurfaceandbottomreflections. . . . 151
D.1 Comparisonofthepredictedandexperimentaldelaytimesforthe
surfaceandbottomreflections. . . . . . . . . . . . . . . . . . . . . 162
vii
E.1 Sedimentparametersforgeoacousticmodelling. . . . . . . . . . . 165
viii
L F
IST OF IGURES
2.1 Illustrationofk-foldcross-validation . . . . . . . . . . . . . . . . 12
2.2 Illustrationofoccurrenceofpositiveandnegativeeventswiththree
examplethresholdsshown. . . . . . . . . . . . . . . . . . . . . . 14
2.3 Confusionmatrixforthetwo-classclassificationproblem. . . . . . 15
2.4 ExampleROCcurves . . . . . . . . . . . . . . . . . . . . . . . . 16
2.5 IllustrationofexcellentaccuracyandAUC,andpooraccuracybut
excellentAUC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1 Example spectrograms of real and synthetic bowhead and hump-
backvocalizations. . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.2 Spectrogramsofanexamplebowheadvocalizationdemonstrating
theeffectsofsignaldenoising. . . . . . . . . . . . . . . . . . . . 22
3.3 Spectraofbiogenicandsyntheticwhalevocalizations. . . . . . . . 24
3.4 Comparisonofauralclassifierdecisionregionsfor(a)biogenicand
(b)syntheticbowheadandhumpbackwhalevocalizations. . . . . . 26
3.5 Transmitting voltage response (TVR) curves for the ITC-2010
transducer and the complete amplifier and ITC-2010 transducer
system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.6 Spectra for full-band and bandpass filtered (a) bowhead and (b)
humpbackwhalecalls. . . . . . . . . . . . . . . . . . . . . . . . 29
3.7 Resultsof trainingthe classifieron (a)fullband, and(b) bandpass
filtered,biogenicbowheadandhumpbackvocalizations. . . . . . . 30
4.1 (a) Map of the experimental location. (b) Map with ship tracks
shown for both days of the experiment, including location of the
recorders,CTDcasts,andFFCPTmeasurements. . . . . . . . . . 35
4.2 Representationoftheexperimentalsetup. . . . . . . . . . . . . . 37
4.3 Ambient noise spectra for day 1 and day 2 of Gulf of Mexico
experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.4 Sediment type, in terms of the Robertson zone, obtained from
FreefallConePenetrometermeasurements. . . . . . . . . . . . . . 42
ix
4.5 Soundspeedprofilesobserved(a)on30April2017,and(b)1May
2013. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.6 Envelopeof matched-filterresults showing arrivalstructure ofan
exampleLFMrecordedontheResonmonitorhydrophone. . . . . 49
4.7 Sound speed profiles used to calculate the transmission loss for
estimating the source level from signals recorded on the monitor
hydrophone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.8 Decision Regions for the biogenic bowhead and humpback calls
that were generated by training on data from (a) the monitor hy-
drophone andtesting on data transmittedover (b)1km, (c) 5km,
and(d)10km. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.9 DecisionRegionsforthesyntheticbowheadandhumpbackcalls
that were generated by training on data from (a) the monitor hy-
drophone andtesting on data transmittedover (b)1km, (c) 5km,
and(d)10km. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.10 Experimentalclassificationperformanceasafunctionofrangefor
thebiogenicwhalecalls. . . . . . . . . . . . . . . . . . . . . . . 59
4.11 Experimentalclassificationperformanceasafunctionofrangefor
thesyntheticwhalecalls. . . . . . . . . . . . . . . . . . . . . . . 60
4.12 ExperimentalclassificationperformanceasafunctionofSNRfor
thebiogenicewhalecalls. . . . . . . . . . . . . . . . . . . . . . . 62
4.13 ExperimentalclassificationperformanceasafunctionofSNRfor
thesyntheticwhalecalls. . . . . . . . . . . . . . . . . . . . . . . 63
4.14 Impact of transmission range of the signals used for training and
validatingtheclassifieronitsperformance. Signalswererecorded
bytheSharpuniton1May2013. . . . . . . . . . . . . . . . . . . 66
4.15 Impact of transmission range of the signals used for training and
validatingtheclassifieronitsperformance. Signalswererecorded
bytheicListensystemdeployedonmooring4on1May2013. . . 67
5.1 TimeandfrequencyresponseofthesincfunctioninputtoWATTCH
togenerateanenvironment’schannelimpulseresponse. . . . . . . 79
5.2 ComparisonoftransmissionlossvaluesdeterminedfromtheWATTCH
model and those predicted using spherical spreading with Thorp
attenuation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.3 Comparison of arrival time series generated by the OASES and
WATTCHmodels. . . . . . . . . . . . . . . . . . . . . . . . . . . 84
x
5.4 Schematic of environment configuration used to simulate the ex-
perimentalacousticpropagationconditions. . . . . . . . . . . . . 86
5.5 Incoherenttransmissionlossmodelledatf =2kHzusingBellhop
fortheenvironmentdepictedinFigure5.4. . . . . . . . . . . . . . 89
5.6 Schematicrepresentationofnoiseaddition to asignalpropagated
throughtheWATTCHmodel. . . . . . . . . . . . . . . . . . . . . 90
5.7 Classificationperformanceasafunctionofrangeforthesimulated
biogenicwhalecallsthatwerepropagatedthroughtheWATTCH
model,comparedwithexperimentalresults. . . . . . . . . . . . . 92
5.8 Classification performance as a function ofSNR for the simulated
biogenicwhalecallsthatwerepropagatedthroughtheWATTCH
model,comparedwithexperimentalresults. . . . . . . . . . . . . 93
5.9 Incoherenttransmissionlossmodelledatf =2 kHzusingBellhop
forfourdifferentsoundspeedfields. . . . . . . . . . . . . . . . . 98
5.10 Sensitivityofclassificationperformancetochoiceofsoundspeed
profile as a function of range for the biogenic whale calls propa-
gatedthroughWATTCHmodel. . . . . . . . . . . . . . . . . . . . 99
5.11 Sensitivityofclassificationperformancetochoiceofsoundspeed
profileasafunctionofSNRforthebiogenicwhalecallspropagated
throughWATTCHmodel. . . . . . . . . . . . . . . . . . . . . . . 100
6.1 Comparison of classifier performance versus range for the noise-
only,propagation-only,andnoiseandpropagationcases. Effectsof
addingexperimentalorwhitenoisearealsoconsidered. . . . . . . 108
6.2 Comparison of classifier performance versus SNR for the noise-
only,propagation-only,andnoiseandpropagationcases. Effectsof
addingexperimentalorwhitenoisearealsoconsidered. . . . . . . 109
6.3 Incoherent TL curves modelled at f = 4kHz for anti-duct or
downwardrefractingSSPs. . . . . . . . . . . . . . . . . . . . . . 113
6.4 Comparisonofclassifierperformancefortheanti-ductenvironment
versus(a)rangeand(b)SNRwheneitherAWGN,orbothAWGN
andpropagationeffectsareaddedtothebiogenicsignals. . . . . . 115
6.5 Comparisonofclassifierperformanceforthedownwardrefracting
environment versus (a) range and (b) SNR when either AWGN,
orbothAWGNandpropagationeffectsareaddedtothebiogenic
signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
6.6 Incoherent TL fields modelled at f = 4kHz for the (a) anti-duct
and(b)downwardrefractingenvironments. . . . . . . . . . . . . . 118
xi