Activity 1.1 - Can we use sound to “see”?

Learning Aims:
  • To explain the concept of echolocation
  • To explain how sound can be used to measure distanceTo determine an unknown length of a tube by using the echo method
Materials:
A computer, a sound sensor, interface and software that displays sound waveforms (e.g. CMA Coach 6), a cartoon or plastic hollow tube
Suggestions for use:

Start by giving the students the activity 1 worksheet. Let them first discuss the questions with their classmates and then write their answers.
Let them read the explanation given in the activity 2 worksheet and discuss with the whole class what echolocation is, how bats use it to navigate and find their food. Discuss other applications of echolocation. At the end of the discussion ask the question ‘Can blind people use echolocation to “see”?’ Let them formulate their hypothesis.
To check their hypothesis show the discovery channel movie ‘Real-life Bat Man” http://dsc.discovery.com/videos/is-it-possible-real-life-bat-man.html. Discuss the movie with students, rise questions and act as a facilitator.

In activity 4 students apply learned concepts. Based on the echo time method they have to determine an unknown length of a tube. In this experiment a sound sensor, data-logger and computer are used. Students record sound signal of the initial sound and echoes. They read thThe activity 3 is an Explanation activity. Students should realise how to calculate the distance covered by sound waves, based on the measured interval time of echo and speed of sound (notice that echo time covers double distance).

e echo time from a graph. Based on the echo time and speed of sound in air they calculate the length of the tube.

The final conclusion at the end of this lesson should be that (ultra)sound can be used to measure distances.

Another nice application of this idea is a motion detector. If you have such device you can show it and let student measure different distances in class. Again discuss how computer knows what the measured distance is.
Possible questions:
  • Do you know other animals than bats, which make use of echolocation?
  • Do you know other applications of echolocation?
  • What is ultrasound?
  • What is the speed of sound in air? In water?
  • Does the speed of sound depend on the medium (air, water, etc..)?