S S V Guillermo Jiménez Rebecca Snyder Brian Heath SOUND SOURCE VERIFICATION Sound Field Sound source Environment Impact of Sound Mitigation SSV SOUND SOURCE VERIFICATION What does the sound field look like ID: 1025078
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1. Sound Source VerificationSSVGuillermo JiménezRebecca SnyderBrian Heath
2. SOUND SOURCE VERIFICATIONSound FieldSound sourceEnvironmentImpact of Sound MitigationSSV
3. SOUND SOURCE VERIFICATIONWhat does the sound field look like?How is the sound perceived by the animal?How can we minimise the impact?SSV
4. Sound field of seismic surveys: two mapping methods presented.Generate high density SPL map around the source.Estimate mitigation zones using the SPL map either:Directly orIndirectly, to validate or refine a previous sound propagation modelPRESENTATION OVERVIEWData CollectionData ProcessingSPL MapMitigation Zones
5. Sound field of seismic surveys: two mapping methods presented.Generate high density SPL map around the source.Estimate mitigation zones using the SPL map either:Directly orIndirectly, to validate or refine a previous sound propagation modelPRESENTATION OVERVIEWData CollectionData ProcessingSPL MapMitigation Zones
6. Sound field of seismic surveys: two mapping methods presented.Generate high density SPL map around the source.Estimate mitigation zones using the SPL map either:Directly orIndirectly, to validate or refine a previous sound propagation modelPRESENTATION OVERVIEWData CollectionData ProcessingSPL MapMitigation Zones
7. Sound field of seismic surveys: two mapping methods presented.Generate high density SPL map around the source.Estimate mitigation zones using the SPL map either:Directly orIndirectly, to validate or refine a previous sound propagation modelPRESENTATION OVERVIEWData CollectionData ProcessingSPL MapMitigation Zones
8. Sound field of seismic surveys: two mapping methods presented.Generate high density SPL map around the source.Estimate mitigation zones using the SPL map either:Directly orIndirectly, to validate or refine a previous sound propagation modelPRESENTATION OVERVIEWData CollectionData ProcessingSPL MapMitigation Zones
9. Mitigation ZonesSound field of seismic surveys: two mapping methods presented.Generate high density SPL map around the source.Estimate mitigation zones using the SPL map either:Directly orIndirectly, to validate or refine a previous sound propagation modelPRESENTATION OVERVIEWData CollectionData ProcessingSPL MapSPL MapPropagation Model
10. The exclusion area is circular for mitigation purposes.The actual area delimited by the threshold level might not be circular.190 dB Mitigation ZoneExclusion Area or Mitigation ZoneSOUND SOURCE VERIFICATION
11. SOUND SOURCE VERIFICATION190 dB Mitigation ZoneThe exclusion area is circular for mitigation purposes.The actual area delimited by the threshold level might not be circular.
12. SOUND SOURCE VERIFICATION190 dB Mitigation Zone
13. SOUND SOURCE VERIFICATION190 dB Mitigation Zone180 dB Mitigation Zone
14. SOUND SOURCE VERIFICATION190 dB Mitigation Zone180 dB Mitigation Zone160 dB Mitigation ZoneLow Threshold LevelsLarger mitigation zonesPrevent behavioural impactHigh Threshold LevelsSmaller mitigation zonesPrevent auditory injury
15. The sea is a complex acoustic environmentThe sound field depends on the source, bathymetry, water properties and seabed geology.The environment characteristics vary in space and time.A good SSV approach must:Account for the dynamic nature of the underwater environment.Define a exclusion area (mitigation zone) for each distinct situationSOUND SOURCE VERIFICATION
16. Deployment: drift buoys or towed hydrophonesSource: impulsive source towed by seismic vesselReceiver: electronics + acquisition software + GPS + hydrophonesData collectedAcoustic signal: PCM 16-bit, 2 channels, 88.2 kS/s to 500 kS/sPosition of receiver: GPS and AISPosition of source: AIS and P190/SPSLog report: deployment/retrieval times, source status, etcDATA COLLECTIONSOUND FIELD MAPPING METHODS
17. Direction of CurrentsDATA COLLECTIONDRIFT BUOY DEPLOYMENTSource VesselImpulsive SourceDrifting Buoys
18. DATA COLLECTIONDRIFT BUOY DESCRIPTIONLED beacon: visual localisationRadar reflector: RF localisation Data acquisition unit: electronics, power supply, GPS, satellite tracker FloatHydrophones: pole-mounted, distinct gains (pre-selected)
19. Portable buoys: easy transport, fast and simple assemblyThe buoys are light (~40 kg) ― 2 person team onlyTypical operations: < 8 h (30 min deployment, 6 h drift, 30 min retrieval)Data retrieval after each individual deployment A buoy can cover up to 25 km in fast currentsRecorded shots per deployment: > 12,000 (10 s shot rate, 6 buoys )Field projects included North Pacific and the ArcticLess flow noise – Particularly effective in fast currentsDATA COLLECTIONDRIFTING BUOY DEPLOYMENT ― HIGHLIGHTS
20. Support vessel: no predefined pathSource vessel: survey linesDATA COLLECTIONTOWED HYDROPHONE DEPLOYMENTImpulsive SourceSource VesselHydrophone ArraySupport Vessel
21. DATA COLLECTIONTOWED HYDROPHONE DESCRIPTIONGPS: placed in a high point on shipData acquisition box: acoustics + GPS Tow cable (all lengths supplied) Hydrophones: various gainsInterface: display + keyboard PCDeck cable
22. Acquisition box and cable: compact system, easy installationData acquisition: switch on before survey, switch off after surveyTypical operations: weeks to monthsData retrieved after crew rotation (few weeks) Covers the entire survey areaRecorded shots per day: > 4,000 (10 s shot rate, 12 h deployment)Field trials in the North Sea and North AtlanticRequires no additional resources.DATA COLLECTIONTOWED HYDROPHONE DEPLOYMENT ― HIGHLIGHTS
23. DATA PROCESSINGSource PositionAcoustic SignalReceiver PositionVesselSourceReceiverSPL MapSource
24. SPL MapDATA PROCESSINGSource PositionAcoustic SignalReceiver PositionVesselSourceReceiverSourceReceived SPL
25. SPL MapDATA PROCESSINGSource PositionAcoustic SignalReceiver Position
26. SPL MapDATA PROCESSINGSource PositionAcoustic SignalReceiver Position
27. SPL MapDATA PROCESSINGSource PositionAcoustic SignalReceiver Position
28. SPL MapDATA PROCESSINGSource PositionAcoustic SignalReceiver Position
29. SOUND PRESSURE LEVEL MAPSSPL MAP FOR DRIFT BUOYS
30. SOUND PRESSURE LEVEL MAPSSPL MAP FOR DRIFT BUOYSVarious source positions may be requiredClear image of sound fieldLong distance and angle coverageEasy to interpretIdeal for model verification1 source positionMultiple receiver positions
31. SOUND PRESSURE LEVEL MAPSSPL MAP FOR A TOWED HYDROPHONE
32. SOUND PRESSURE LEVEL MAPSSPL MAP FOR A TOWED HYDROPHONEMay be difficult to interpretLimited distance and angle coverageAccurate representation of sound field variationsIdeal for model refinementMultiple source positionsMultiple receiver positions
33. MITIGATION ZONESDIRECT CALCULATION FROM MEASURED SPL VALUES180170160150140130120SPLrms [dB re 1µPa]Distance [km]
34. MITIGATION ZONESDIRECT CALCULATION FROM MEASURED SPL VALUES180170160150140130120SPLrms [dB re 1µPa]Distance [km]
35. MITIGATION ZONESDIRECT CALCULATION FROM MEASURED SPL VALUES4100 m95th Percentile Curve90th Percentile Curve80th Percentile Curve180170160150140130120SPLrms [dB re 1µPa]Distance [km]
36. MITIGATION ZONESDIRECT CALCULATION FROM MEASURED SPL VALUES95th Percentile Curve90th Percentile Curve80th Percentile Curve3500 m180170160150140130120SPLrms [dB re 1µPa]Distance [km]
37. MITIGATION ZONESDIRECT CALCULATION FROM MEASURED SPL VALUES3200 m95th Percentile Curve90th Percentile Curve80th Percentile Curve180170160150140130120SPLrms [dB re 1µPa]Distance [km]
38. Can be extended with validated propagation model.Measured SPL map: shows variability of sound field.MITIGATION ZONESDIRECT CALCULATION FROM MEASURED SPL VALUESSampling strategy and deployment constraints affect point distributions.
39. Easy deployment, retrieval and implementationCost effectiveVery large datasets (thousands of SPL points)Multiple receiver positionsExtensively tested (Pacific, Atlantic, Arctic, North Sea)Minimal environmental impactFast data collection, analysis and reporting (< 24 hours)SOUND SOURCE VERIFICATIONSUMMARY