This activity page will offer:
Insight into echolocation
activity in reflected sound waves
in calculating distance based upon detection of reflected sound
In this activity, you'll have the opportunity to approximate an
object's distance by analyzing reflected sound waves. As you clap
your hands, you'll send out a sound pulse. When the pulse impacts
a hard surface, the sound is reflected and returns back to the sender.
By analyzing the echo return time, you can calculate the distance
to the reflecting surface. Here's how.
with high vertical wall
watch with digital display
(For the set-up)
- Work with a partner. Use a meter stick and measure a distance
of 20 meters from the high wall of a courtyard.
- Stand at this distance and clap your hands together to produce
a sharp and distinct sound. Listen carefully to detect the echo
that bounces off the reflecting courtyard wall.
- Begin clapping a steady rhythm. Distinguish the clap and its
return echo. Maintain a steady rhythm of about two claps per second.
Practice so your cadence becomes unerring. If necessary, base
your clapping beat on the display of a digital watch.
- Begin to increase the tempo of the clapping. Keep the rhythm
steady. Increase the speed of the clapping until the claps and
echoes coincide. Maintain this tempo and have your partner determine
the number of claps produced in a one-second period.
- Divide the time (1-second) by the number of claps counted to
calculate the time required for the round trip travel of a single
- To uncover the distance traveled by this sound wave, multiply
the calculated time by the speed of sound, 344 m/s.
- To determine the distance to the wall, divide the round trip
distance by two. Compare your calculated distance with the distance
you measured with your meter stick.
- Walk about three times the distance from the reflecting wall.
Repeat steps 4 through 7 to determine your new distance to the
wall. After you make this mathematical calculation; use a meter
stick to measure this distance. How close to the meter stick measurement
was your calculated distance? What might account for any deviation
- Why is there a delay in hearing the sound of the clap and its
- Suppose the speed of sound was 688 m/s. How would this affect
- Why was it important to maintain a steady beat?
and Soft Targets
How might the surface properties of the echolocation target affect
reflected sound waves? Would a hard target produce the same type
of reflection as a softer surface? How would they be the same? How
might they differ? Develop a strategy for inquire that would explore
the relationship between a target's surface hardness and its echo
Write a short play that takes place in the mind of bat. The characters
in this play are sound and echolocation centers of the brain. Create
a dialog in which these centers communicate as they try to calculate
the echolocated distance to an evening meal. Try to maintain a humorous
approach as you integrate real science into the conversation.
Surf the Internet to uncover sites that offer downloadable audio
clips of bat sounds. Listen to these sounds. Note the rhythm, melody
and texture of these different clips. Then, put these sounds into
a repeating loop that forms a steady rhythm track. Play the track
and create your own bat-inspired melodies to the beat of the chirping
and Active Sonar
Submarines also depend upon sound
for accurate navigation and "observation" of unseen objects. Like
the chirping bats, subs use active sonar. They also use something
called passive sonar. Use library and online references to determine
the similarities and differences in these techniques. Then, present
a sound-full presentation to your classmates that distinguish the
two types of sonar
Site that offers all sorts of resources and links (some expired)
Sounds: Echolocation by Blind Humans
An article that surveys the use of echolocation by visually impaired
A variety of bat sound files in WAV and AIF formats
Advisors for this Guide:
Suzanne Panico, Science Teacher Mentor, Cambridge Public Schools,
Anne E. Jones, Science Department, Wayland Middle School, Wayland,
Gary Pinkall, Middle School Science Teacher, Great Bend Public Schools,
Great Bend, KS