using sound for many purposes sound waves have many purposes for both humans and animals ...
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Using Sound for many purposesUsing Sound for many purposes Sound waves have many purposes for both Sound waves have many purposes for both humanshumans and and
animalsanimals Understanding intensity, pitch and the Doppler EffectUnderstanding intensity, pitch and the Doppler Effect has has
enabled scientists to develop complex forms of technology, enabled scientists to develop complex forms of technology, such as ultrasounds, fish-finders, and music-editing such as ultrasounds, fish-finders, and music-editing machines machines
In this section, you will be learning about the following In this section, you will be learning about the following processes:processes:– Acoustics :Acoustics : which is used for designing concert halls and which is used for designing concert halls and
sound-proof rooms sound-proof rooms – Echolocation:Echolocation: which is how bats and dolphins which is how bats and dolphins
communicate, or locate prey and predatorscommunicate, or locate prey and predators– Sonar:Sonar: which is used to map the ocean floor or locate which is used to map the ocean floor or locate
schools of fishschools of fish– Sonograms:Sonograms: which are pictures created of the insides of which are pictures created of the insides of
bodiesbodies What do most of these processes have What do most of these processes have in commonin common??
– Most of these processes involve the Most of these processes involve the use of echoesuse of echoes and and the the use ofuse of ultrasonic wavesultrasonic waves (waves above the human (waves above the human hearing frequency; above 20,000 Hz)hearing frequency; above 20,000 Hz)
EcholocationEcholocation- is the use of reflected sound waves - is the use of reflected sound waves to determine distances or to locate objectsto determine distances or to locate objects
Dolphins and bats rely on Dolphins and bats rely on ultrasonic wavesultrasonic waves (those above (those above 20,000 Hz20,000 Hz) to ) to locate preylocate prey or or communicatecommunicate with other members of their with other members of their speciesspecies
Here’s how it works for dolphins:Here’s how it works for dolphins:– 1. the dolphin sends out the ultrasonic 1. the dolphin sends out the ultrasonic
waveswaves– 2. ultrasonic waves reflect off the prey 2. ultrasonic waves reflect off the prey – 3. the dolphin uses the reflected 3. the dolphin uses the reflected
waves to detect obstacles or preywaves to detect obstacles or prey If the sound reflects back quickly, then prey is If the sound reflects back quickly, then prey is
nearbynearby They also rely on the They also rely on the Doppler EffectDoppler Effect::
– If the pitch is If the pitch is higherhigher, the prey are , the prey are coming coming towardtoward the dolphin the dolphin
– If the pitch is If the pitch is lowerlower, then the prey are , then the prey are moving awaymoving away from the dolphin from the dolphin
Echolocation by Dolphins:A dolphin sends out an ultrasonic wave and detects the reflected wave.
1. The dolphin sends out ultrasonic waves
2. Ultrasonic waves reflect off the fish.
3. The dolphin uses the reflected waves to detect obstacles or prey.
SonarSonar SonarSonar works a lot like works a lot like
echolocation, except that this echolocation, except that this method is used by method is used by machinesmachines
SonarSonar is a system that uses is a system that uses reflected sound waves to detect reflected sound waves to detect and locate objects underwaterand locate objects underwater
The word The word S.O.N.A.RS.O.N.A.R. . comes comes from the initial letters of from the initial letters of sosound und nnavigation avigation aand nd rranginganging
NavigationNavigation means finding your means finding your way around the way around the ocean (or air)ocean (or air) and and rangingranging means finding the means finding the distance between objectsdistance between objects
Today, sonar is used to Today, sonar is used to determine the determine the depthdepth of water, of water, to to mapmap the ocean floor, and to the ocean floor, and to locate locate sunken ships, schools of sunken ships, schools of fish, and other objectsfish, and other objects in the in the oceanocean
How Sonar Works:How Sonar Works: A sonar device sends a A sonar device sends a
burst of burst of ultrasonic ultrasonic waveswaves that travel that travel through waterthrough water
When the sound waves When the sound waves strike an object or the strike an object or the ocean floor, they ocean floor, they reflectreflect, and a , and a hydrophonehydrophone detects detects theses reflected wavestheses reflected waves
The The farther awayfarther away a a sound travels before sound travels before bouncing off an object, bouncing off an object, the the longerlonger it takes to it takes to return to the sonar return to the sonar devicedevice
Ultrasounds/ SonogramsUltrasounds/ Sonograms Doctors use ultrasound imaging to look inside the Doctors use ultrasound imaging to look inside the
human bodyhuman body Ultrasound devicesUltrasound devices send send ultrasonic wavesultrasonic waves into into
the body and detectthe body and detect reflected reflected sound waves sound waves Different partsDifferent parts of the body, such as bones, of the body, such as bones,
muscles, the liver or the heart, muscles, the liver or the heart, reflectreflect soundssounds differently because of their differently because of their densitiesdensities
The device that uses the reflected ultrasonic The device that uses the reflected ultrasonic waves to create a waves to create a picture picture is called a is called a sonogramsonogram
A doctor holds a small probe over a pregnant A doctor holds a small probe over a pregnant woman’s abdomen and the probe sends out a woman’s abdomen and the probe sends out a 4 4 million Hz wavemillion Hz wave, and the device uses the , and the device uses the reflected sound waves to produce a reflected sound waves to produce a sonogramsonogram
Doctors can use sonograms to Doctors can use sonograms to diagnose diagnose patientspatients, or , or find out find out positioningpositioning of a developing of a developing babybaby
They can also detect if They can also detect if more than onemore than one baby will baby will be bornbe born
AcousticsAcoustics You may think of our auditorium when you think of acousticsYou may think of our auditorium when you think of acoustics AcousticsAcoustics is the study of how sounds is the study of how sounds interactinteract with each with each
other and the environmentother and the environment Sound waves can interfere with each other in 2 ways:Sound waves can interfere with each other in 2 ways:
– Constructive interference-Constructive interference- can distort sounds can distort sounds– Destructive interferenceDestructive interference - - can produce dead spots, can produce dead spots,
where loudness is reducedwhere loudness is reduced You can also hear You can also hear echoes echoes as sound waves reflect back and as sound waves reflect back and
forth off hard surfacesforth off hard surfaces This is This is reverberationreverberation, in which the , in which the echoesechoes of a sound are of a sound are
heard afterheard after the sound source stops producing waves the sound source stops producing waves The sound of a handclap can take more than a second to die The sound of a handclap can take more than a second to die
out in a gymout in a gym This is why acoustics is used in the design of This is why acoustics is used in the design of concert hallsconcert halls to to
control control interferenceinterference and and reverberationreverberation
Different surfaces change the Different surfaces change the amount of reverberationamount of reverberation
CurvedCurved, hard surfaces are used to , hard surfaces are used to direct sounddirect sound waves to different parts of the concert hall waves to different parts of the concert hall – Curved wallsCurved walls– Wooden panelsWooden panels– High ceilingsHigh ceilings
SoftSoft surfaces surfaces absorbabsorb sound waves sound waves, reducing , reducing reverberation reverberation – Cloth or velvet curtainsCloth or velvet curtains– Carpeted floors and wallsCarpeted floors and walls– Seat cushionsSeat cushions
But some reverberation But some reverberation is is goodgood, otherwise instruments , otherwise instruments would would sound thinsound thin and and distantdistant
With too much reverberation, reflected waves interfere With too much reverberation, reflected waves interfere and and individual notes become individual notes become hard to pick outhard to pick out