Technical Search

8/9/2019 Technical Search

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Technical Search Considerations Listening Techniques


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D escribe the applications for listening devicesIdentify the prime factors affecting soundpropagation and explain how materials affect it


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D ifferentiate between detecting and locatingD escribe the importance of making a searchplanD escribe the purpose of record keeping and

the basic documentation methods used


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Sensation produced by vibrations transmittedthrough airMechanical vibrations transmitted through anelastic mediumParticular auditory effect produced by a givensourceNoise, vocal utterance, and musical tone


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These instructions

are printed on theinside of minershard hats


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B asic considerationsD etecting versus locatingSensor spacing

Circle of detection


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30 m

15m

8m

5 mScratching

Tapp ing wi th F inge r

K n o c k i n g w i t h F i s t

K n o c k i n g w i t h R o c k


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S ensor 1 S ensor 2

Possible location is astraight line between

sensors

Sensors show equalloudness

1 2


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Possible locationof signal source

Sensors show unequal loudness

S e n s o r 1S e n s o r 2 h a l f a s l o u d a sS e n s o r 1

S e n s o r 2

S e n s o r 1 S e n s o r 2 o n e t e n t h a s l o u d a sS e n s o r 1

S e n s o r 2

S e n s o r 1

S e n s o r 2 o n e t h i r d a s l o u d a sS e n s o r 1

S e n s o r 2


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S e n s o r 1 S e n s o r 1S e n s o r 2 S e n s o r 2

S e n s or 3 S e n s o r 3

S e n so r 1

S e n s o r 2

S e n so r 3


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S ensor 1 same as S ensor 2, loud

Leave S ensor 1 and S ensor 2alone. Move S ensor 3 and S ensor 4 which way?

Nice symmetrical layout, but nowall sensors have the same signal.

Easy

Difficult

Better

For detection, you can move in straight line or in blocks.

For locating or Triangulation operator should move 90 to base line if

sensors were started with straight line pattern.


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A ll sensors have same loudness

2 sensors loud, 2 sensors faint

1 sensor loud, 3 sensors faint


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If a large building:2 sensors per wall

Perfectly round pileRemember: All sensors will show equal loudness if the source is in the center!

Building: Start with foundation, place sensor at center of walls.

Pancake CollapseDetection: Layer by layer or up and

down each sideLocating: Stay on one layer

Building: S tart with foundation, placesensor at center of wall.

If a large building, 2sensors per wall.

Pancake Collapse:

Detection: Layer by layer or up and down eachside.

Locating: S tay on onelayer.

Perfectly round pile: Remember: A llsensors will show equal loudness if the source is in the center!


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A ssess site

Sketch bookSafety aspectsTalk to witnessesConsider structureSurface search

Check accessible voids

Stimulate responsefrom a victimPrimary searchListen to majorstructural partsGo for most probablelocations


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Call out/listen search may be effective (low density

of wood floors)A coustic listening devices probably more effectivethan seismic in building with wood floors and walls

Canine should be able to scent through cracks inwood floor if they are not heavily covered


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Call out/listen search may be effective (low densityof wood floors)

A coustic listening devices probably more effectivethan seismic in buildings with wood floors/badlybroken masonry walls

Canine should be able to scent through cracks inwood floor if they are not heavily covered


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Callout/listen search may not be effective due tohigh density of concrete floors

Seismic listening devices can be most effective inpancake type collapse

Canine will indicate direction of scent which mayflow around large slabs, back and forth acrossbuilding


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Callout/listen search may be effectivedepending on compactness of rubble

Effectiveness of listening devices dependenton interconnection of collapsed structuralparts

Canine may be able to scent throughopenings in debris


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Loose sections above

Gas, electricity, waterUnstable sectionsunderfootHazardous material


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CommunicationsEstablish signals

Immediate evacuationWithin the team

D ivision A ssignmentsSearch and Rescue integrated into ICSTeams may be separated from slower, more time-consuming rescue efforts


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2 sensors in circular pattern


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Instruct to knock three

timesInstruct to rest whilesensor set-up changedSpecialist knock three

times with heavy rockagainst part of structure

Photo courtesy of Uwe Beckmann


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Clean, hard surfaceSolid parts of structurePipes carry sound great distance

Use with caution when trying to pinpoint locationof victim


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Side View

V-Type Collapse

Top View

V- Type Collapse

S ide V iew

Top V iew


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Side View

Lean to

Top View

Lean to

S ide V iew

Top V iew


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Side View

P a n C a k e

Top View

Pancake

S ide V iew

Top V iew


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Mine shaft

Shaft

Shaft

S ide V iew

Top V iew


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Buried vehicle

S ide V iew

Top V iew

S i de V i ew

B ur i e d Ve h i l e

Top V i ew


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WindCover and place sensors inside

Rain, sleet, and hailUse cloth, non-contacting rubble pieces

Running waterD eal with promptly to prevent flooding of voids

A irborne soundUsually not critical


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V ibrationsCut off low frequencies if device has adjustablefiltering

D iamond sawCut high end of frequency band


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J ack hammerMust be shut off during listening time

Interference from workWalking/digging must stop during listening time

A ircraftF ilter for low frequency vibration


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F orms of InformationA udible warning signalsOral reportsV

isual signals


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Produce accurate information

Provide complete informationCommunicate hazardsSpeed up tasks

Enable re-creation of a situation


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Some records work papers, some permanentSimple logSite plan sketch

Review site safetyGet complete picture of collapse

Identify potential void spacesF ind good sensor locationsD evelop search plan

Voice recording

Documents

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