Echolocation
Sending out ultrasound waves and interpreting the returning sound
echoes is called echolocation (echo + location). Bats flying at night
find their meals of flying insects by using echolocation. They send out as
many as 200 ultrasound squeaks per second. By receiving the returning
echoes, they can tell where prey is and how it is moving. They can also
veer away from walls, trees, and other big objects.
sound waves
emitted by bat
VOCABULARY
Make description wheels
for the terms echolocation
and sonar to help you
remember them later.
sound waves
reflected off prey
A number of animals that live in water use echolocation, too.
Dolphins, toothed whales, and porpoises produce ultrasound squeaks
or clicks. They listen to the returning echo patterns to find fish and
other food in the water.
Sonar
People use the principles of echolocation to locate objects underwater.
During World War I (1914–1918), scientists developed instruments
that used sound waves to locate enemy submarines. Instruments that
use echolocation to locate objects are known as sonar. Sonar stands
for “sound navigation and ranging.” The sonar machines could detect
sounds coming from submarine propellers. Sonar devices could also
send out ultrasound waves and then use the echoes to locate underwater
objects. The information from the echoes could then be used to form
an image on a screen.
Later, people found many other uses for
sonar. Fishing boats use sonar to find schools
of fish. Oceanographers—scientists who study
the ocean—use it to map the sea floor. People
have even used sonar to find ancient sunken
ships in deep water.
This woman is using sonar
to monitor for submarines.
Sonar is used to locate sunken ships. The image
of the sunken ship above was produced on the
basis of information from sonar.
Chapter 14: Sound 491