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ACOUSTICAL OCEANOGRAPHY

Unit 2. Lesson 4. Equipment andSounds People use to Explore the

OceansLesson Objectives: Students will gain knowledge and appreciation for research vesselsand equipment found on them.

Vocabulary words: satellite, Argos, tether, autonomous, buoy, iodiophone

Vessels and Vehicles

Vessels

The ocean providesoceanographers will a difficultenvironment to study. Deepwater, high pressure, and lowlight all hinder oceanexploration. In many cases is itnecessary to reach locations far from land, conduct experimentsover a long period of time, andbring samples and specimens

almost any kind of equipment,and satellite equipment to

transmit data back to land.Ships are equipped withwinches, cranes, A-frames,small boats, and other gear todo over-the-side work. Theyalso have laboratory space for sample analyses and dataprocessing. Most ships stay

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bring samples and specimens processing. Most ships stay


include manned, andunmanned submersibles,

remotely operated vehicles,buoys, CTD’s and other sampole collection devices, likebottles and nets.

At any given time, it might bepossible to find vessels in the

Pacific Ocean, the Polar Regions, Lake Baikal, and theMediterranean Sea, as well asalong coastlines.

S ATELLITES

The world’s oceans containalmost 3,000 drifters, buoys,and other objects collectingoceanographic data. Theseitems are monitored by the onlysatellite system dedicated to

transmissions from floating anddeep-sea buoys and other platforms. The message isthen transmitted back to a landor ship-based operation. Theland-based scientist can easily

retrieve the datawithout removing theinstrument from thewater and dataanalysis can beginimmediately using the

Argos system.

The most attractiveaspect of using drifting

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Robots

Advancement in technologyhas allowed the use of unmanned and untetheredrobots. Created and designed

at Woods Hole OceanographicInstitution, ABE is the first of itskind, and still in thedevelopment stages. ABEstands for AutonomousBenthic Explorer. It wasdesigned because scientistshave the need to monitor anarea over long period of time,and go very deep. ABE will be

a set of tasks over severalmonths.

ABE has a ‘body’, muscles(thrusters), nerves (cabling

power to operate the motor,cameras, and sensors), andbrain (computer systems for power, and determining whereto go and makemeasurements). The data willnot be available until the

instrument is recovered.

Initially, ABE will only be able toperform the tasks that it is pre-programmed to do, but astechnology advances that isexpected to change.Ultimately, scientists hope touse underwater acoustic datatransmission systems to allow

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The size of the buoy variesdue to the instruments that it

carries, and also dependingon the length of time that thebuoy is to remain in the water.The buoys are dropped in the

ocean using a large crane ona research vessel, and left

unattended until the vesselretrieves it. Some of the areequipped with satellitetransmitters.

Sound Used in Ocean Research

There are four major categoriesof sound exploration. The firstinvolves the use of receivingdevices called hydrophones.Hydrophones listen to ambient

or background, noises such asthose emitted by whales, fish or submarines. The second isSOund Navigation AndRanging, abbreviated SONAR.This involves sending andreceiving signals reflected from

objects (fish, submarines)within the water or the seabed.Using the time it takes thei l t t t th i

difference betweenecholocation and SONAR,except that echolocation ismuch more informative thanSONAR. It allows much more

detail and description to beinterpreted, where SONARfinds objects and the distancethey are away. Marinemammals that use echolocationcould distinguish if something isa live animal, or an object.

Finally, sidescan-imaging systems produce the equivalentof aerial photographs or radar i i d Th

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Future of Ocean ResearchOcean Research is bigbusiness. It is important toresearchers, engineers,politicians, mining, fisheriesand marketing business

people. As technologyadvances, so does theequipment used for oceanresearch. More data areavailable, better resolution isachieved, and continuousdata collection is now possible

through satellite monitoring.What is even more exciting isthat scientists can often forgothe lengthy and expensiveresearch trips that have been

customary in the past!! Thestudy of the ocean is onlygoing to become morecomplete and more accurateas technology continues toadvance.

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Activity 4-1. Phone a Friend

Alexander Graham Bell built the first telephone. Many years ago, it wasnecessary to lay underwater cables across the ocean for people to call acrossthe ocean. Today, cables are not necessary, and the signals are bouncedthrough satellites as waves. Experiment with the following activity to understandhow sound travels.

Materials and MethodsHammer Nail2-3 empty 540 mL cansheavy stringa friend

Procedure:1. Use a hammer and nail to punch a hole in the center of the bottom of each can.

2. Cut a piece of string 7m (21feet) long. Push one end though each endof the can, and tie the string so that the knot is inside the can.

3. With your friend, take the phone outside and hold the cans far enoughapart so that the string is stretched tightly.

4. Talk into the can while your friend holds the can to his/her ear.5. Make the same phones with strings of other lengths and notice howsound is different.

6. Now add a third person. Tie a string, with can attached to the middle of

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Activity 4-2. Play the Table Settings

Have you ever tapped your fingernail on a glass, drummed your finger on a closed can of vegetables, or rubbed your finger across therim of your glass? Have you ever scraped your fingernails over thechalkboard or a mirror??! This is called playing an idiophone. InGreek, Idio - means self and phone means sound. An idiophone is

something that naturally makes sounds when it is rubbed, struck,shaken or scraped.

Materials:Water Several wine glasses

Procedure:1. Fill the wine glasses with different amounts of

water.2. Wet a fingertip, and rub it on the rim of each

glass until it ‘sings’.

HHooww iitt wwoorrkkss Look at the water! It vibrates as the glass vibrates. The water inthe glass slows down the vibration down. That is why the glass

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©PROJECT OCEANOGRAPHY SPRING 2000

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Unit 3. Lesson 4. Student Activity Sheet 4. How to Live on a Ship

This is the inside of a research vessel atWoods Hole Oceanographic Institution

How would you liketo spend several monthson a ship this size?

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