Tell your students that a decibel (dB) is a unit used to measure the intensity of a sound. The intensity of sounds is expressed using the decibel scale. The smallest audible sound, which is near total silence, is 0 dB. A sound 10 times as loud is 10 dB. A sound of 50 dB is five times as loud as a sound at 10 dB, and so on.
Have your students guess the dB of the following sounds.

  • lawnmower (90 dB)
  • whisper (15 dB)
  • rock concert (120 dB)
  • normal conversation (60 dB)
  • firecracker (140 dB)
  • car horn (110 dB)
  • jet engine (120 dB)

After this, point out that any sounds above 85 dB can cause hearing loss depending upon length of exposure. Any exposure to 140 dB sounds or above can cause immediate damage.