Operation BANG

Day 1: And There Was Sound, Part 2

Science of Sound

Objective: Students understand the concepts of frequency/pitch, intensity/loudness/volume, and hazardous/dangerous noise.

Directions:

  1. As an attention step, brainstorm various activities that generate loud, potentially dangerous noise. Describe that noise is vibration and has two characteristics: frequency and intensity.
  2. Frequency demonstration: Use tuning forks, glasses filled with differing amounts of water, piano, pitch pipe or other musical instruments, etc. to demonstrate high and low pitch. Let volunteers demonstrate the props for you to increase attention.
    • Alternate: Line students up in classroom to represent air molecules. Generate high and low frequency sounds and have the students sway accordingly.
  3. Intensity demonstration: Turning the volume up on a transistor radio is a simple way of showing loudness. You can use the students from #2 above represent loudness also by swaying into each other harder and softer but not faster or slower.
  4. Noise Thermometer: Explain the noise thermometer. Below 85 is safe, over 85 is potentially dangerous. Also, explain that not only is volume important, but the time you’re around the sound is important. Explain that the louder the sound gets, the faster it can harm your hearing. [See attached script]
  5. Noise controls: Demonstrate noise controls by holding a vibrating noise source (music box, tuning fork, etc.) in the air. Then, place the same object on a hard surface (overhead transparency, desk, floor, etc). The sound should get much louder. Explain that vibrating objects touching hard surfaces are often the cause of loud noise. A noise control, or engineering control, may make the sound quieter. Demonstrate this by placing the vibrating object on a rubber pad, o-rings, etc.
  6. Homework: color the noise thermometer.

Materials Needed:

  • Transistor radio
  • Objects of varying frequencies
  • Noise source (tuning fork, music box, etc.)
  • Rubber pad, O-rings, etc.

The Noise Thermometer Exercise

This exercise is a method to teach time/intensity ratios. These time/intensity ratios are designed after but are not identical to the occupational Permissible Exposure Limits (PEL) as outlined in the Department of Labor Noise Exposure Standard 1910.95. This exercise is designed to teach students how to estimate volume levels and the corresponding time period of exposure to that volume that will result in a noise-induced hearing loss. In other words, how loud is too loud and how long is too long.

  1. Draw the thermometer on board. Interact with the children regarding what it is and how a thermometer is used.
  2. Explain that this is a Noise Thermometer designed to show how loud the things in our lives are.
  3. Have the children draw a thermometer of their own on their paper in the middle from the very top of the page to the very bottom. Make sure to leave room on either side of the thermometer for writing.
  4. In the top left corner write the word “decibel”. Tell the children to do the same. Below the word “decibel” write the following definition: “A way to measure loudness”
  5. Review with the children what a definition tells about a word. As well interact with the children about the word “measure”. Analogies such as a measuring cup or a ruler are helpful.
  6. At the bottom of the thermometer, on the right side, write the number 0 for 0 decibels. Next to the 0 write “very soft” to indicate how loud 0 decibels is. Explain to the children that 0 decibels is not silence but a sound that is very soft.
  7. Approximately one-third of the way up the thermometer, again on the right side, write the number 60. Ask the children if 60 decibels is louder or softer than 0 decibels. Explain that 60 decibels is the loudness level of talking and that you are talking to the children at about 60 decibels. Next to the number 60 write the word “talking” to indicate how loud 60 decibels is.
  8. Slightly more than one-half of the way up the thermometer, on the right side, write the number 85. Ask the children if 85 decibels is louder or softer than 60 decibels. Then ask the children what in their lives do they think is 85 decibels. Explain to the children that 85 decibels is the loudness level of street traffic. Next to the number 85 write the word “traffic” to indicate how loud 85 decibels is.
  9. Tell the children that 85 decibels is also very special because it is this level that starts hurting hearing. Ask the children if this means that every time they go out onto the street that they need to use hearing protection. Explain to the children that 85 decibels is harmful to hearing but it takes 8 hours. On the left side of the thermometer at the level of 85 decibels write “8 hours” to indicate how long it will take before 85 decibels becomes harmful to hearing. Tell the children if they do not sit on the street corner pushing the crosswalk button for 8 hours straight then they do not have to use hearing protection.
  10. Two-thirds of the way up the thermometer, on the right side, write the number 100. Ask the children if 100 is louder or softer than 85 decibels. Ask the children what in their lives could possible reach 100 decibels. Explain to the children that 100 decibels is the loudness level of the average stereo headset. Next to the number 100, write the words “stereo headset” to indicate the volume level of 100 decibels.
  11. Ask the children if 85 decibels takes 8 hours to hurt hearing will 100 decibels take longer or shorter time to hurt hearing. Allow the children to guess until someone guesses 2 hours. On the left side of the thermometer at the level of 100 decibels write “2 hours” to indicate how long it will take before becomes harmful to hearing.
  12. Three-quarters of the way up the thermometer, on the right side, write the number 120. Ask the children if 120 decibels is louder or softer than 100 decibels. Ask the children what in their lives could possibly reach 120 decibels. Explain to the children that 120 decibels is the loudness level of a rock concert. Next to the number 120, write the words “rock concert” to indicate how loud 120 decibels is.
  13. Ask the children if 85 decibels takes 8 hours to hurt hearing and 100 decibels takes 2 hours, will 120 decibels take longer or shorter time to hurt hearing. Allow the children to guess until someone guesses 7 and one-half minutes. On the left side of the thermometer at the level of 120 decibels write “7 1/2 minutes” to indicate how long it will take before 120 becomes harmful to hearing.
  14. Tell the children that rock concert last longer than 7 1/2 minutes so how are they going to go to the whole concert without hurting their hearing? Explain to the children that hearing protection allows them to go to the whole concert without hurting their hearing. If this sounds silly to them (and it will), tell them that many of the musicians are wearing hearing protection. The musicians know the loudness level is harmful, we should, too.
  15. At the very top of the thermometer, on the right side, write 150 decibels. Ask the children if 150 decibels is louder or softer than 120. Ask the children what in their lives could possibly reach 150 decibels. Explain to the children that 150 decibels is the loudness level of gunfire. Next to the number 150 write the word GUNFIRE to indicate how loud 150 decibels is.
  16. Ask the children if 85 decibels takes 8 hours to hurt bearing and a rock concert takes 7 1/2 minutes to hurt hearing, how long will it take for 150 decibels to hurt hearing? On the left hand side of the thermometer at the level of 150 decibels write the words “less than 1 minute” to indicate how long it will take before 150 becomes harmful to hearing.