Activity 1.8 - How loud is too loud?

Learning Aims:
  • Understanding that sound intensity (loudness) is measured in decibels
  • Understanding that exposure to very loud sounds can cause damage to hearing
Materials:
A sound sensor, interface and software that displays sound waveforms (e.g. CMA Coach 6), a sound source, a shoe box, different isolation materials like cotton wool, fabrics, egg boxes, foam, newspaper, etc.
Suggestions for use:

Divide the class into small groups to work with computers, hand out Classroom Material: Sound protection (Part I). Let students perform computer investigations to determine the sound intensity of different sound sources and to determine the best sound insulator. Once students completed their investigations discuss their results.

Then hand out Classroom Material: Sound protection (Part II). Have students research the effects of sound on their health (Research assignment: How loud is too loud?). In their investigation they can use a nice interactive animation – ‘Interactive sound ruler’ available via http://www.nidcd.nih.gov/health/education/decibel/decibel.asp.

Then use protective earmuffs to show students and have a class discussion on why different professions might need to use these, and what would be the effects for these people if the ear protection is not worn. Discuss the possible damages loud sounds can have on human hearing.

This lesson would be an excellent time to invite an audiologist to visit the class. Have students write questions for the speaker on slips beforehand. In this students should be encouraged to relate their question with the research assignment.
Possible questions:
  • Why do you think construction workers wear earmuffs?
  • Can you think of any other profession who need to wear ear protection?
  • What might happen if these people don’t wear ear protection?
  • Which material is the best at stopping sound?
  • Which material is useless at stopping sound?
  • Does the twice the thickness of the material stop the sounds any better?