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Chapter 16.5: Using Sound. Pg. 564-567. Echolocation. Echolocation is the use of reflected sound waves to determine distances or to locate objects Animals, including bats and dolphins, use echolocation to navigate and find food. Echolocation: Bats.
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Chapter 16.5: Using Sound Pg. 564-567
Echolocation • Echolocation is the use of reflected sound waves to determine distances or to locate objects • Animals, including bats and dolphins, use echolocation to navigate and find food
Echolocation: Bats • Bats use ultrasound waves with frequencies up to 100,000 Hz to move around and hunt • As bats fly they send out short pulses of ultrasound waves • About 200 pulses per second! • Ultrasound waves reflect off objects and return the bat’s ears • The time it takes for the sound to return to the bat lets the bat know how far away the object is
Echolocation: Dolphins, Porpoises, and Whales • Some animals must hunt in darkness • Dolphins send out ultrasound waves with frequencies as high as 150,000 Hz • The sound waves travel through the water and bounce off fish or prey • Dolphins sense the reflection through their jawbones
Ultrasound Technologies • Ultrasound technologies such as sonar and ultrasound imaging are used to observe things that cannot be seen directly
Sonar • Sonar is a system that uses reflected sound waves to detect and locate objects underwater • SOund • Navigation – finding your way around on the ocean/air • And • Ranging – finding the distance between objects • Sonar is used to determine the depth of water, map the ocean floor, locate sunken ships, find schools of fish
How Sonar Works: • A sonar device sends a burst of ultrasound waves that travel through water • When the sound waves strike an object or the ocean floor they reflect • The sonar device detects the reflected waves • The farther a sound waves travels without bouncing off and object, the longer it takes for it return to the sonar device
How Sonar Works: • A computer in the sonar device measures the time it takes for the sound waves to go out and return • It multiples this time by the speed of sound in water, which = the total distance the sound waves traveled • This total distance is then divided by two because the sound waves traveled out and back
Ultrasound Imaging • Doctors use ultrasound imaging to look inside the human body • Ultrasound imaging devices send ultrasound waves into the body and detect the reflected sound waves • Different parts of the body reflect sound differently • The device uses the reflected ultrasound waves to create a picture called a sonogram • Sonograms can be used to diagnose and treat many medical conditions
Ultrasound Imaging • Ultrasound imaging is used to examine developing babies before they are born • A small probe is placed on a pregnant woman’s abdomen • The probe sends out very high frequency ultrasound waves (4 million Hz) • The reflected sound waves are analyzed by the device and a sonogram is produced • The sonogram can show the position of the baby and how many babies are going to be born