Determine the Speed of Sound in Your Classroom

Here's my latest addition to the FLOSScience site. In this installment I introduce a procedure for determining the speed of sound in your classroom. As usuall, below is only the first part of the procedure. For the full procedure you'll need to this entry on the FLOSScience Probeware Site.

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will go through a process that will allow you to determine the speed sound travels out to four significant figures with less than a 3% error. This is a classic physics lab that in the past would have required lots of expensive equipment to ensure this degree of precision and accuracy. The only expensive equipment involved here is a computer with a microphone input. Which by itself can be expensive, but most classrooms these days have at least one in the room.

Step one -Stuff You Need

1. Computer with microphone input.
2. Microphone you can plug into the computer. I use some cheap headsets that I bought on ebay for $4.50 each. Really any microphone that you can plug into your computer will do (even USB microphones).
   
3. Long tube, 1.5 m to 2 m in length is best. You can use PVC pipe, but I typically use "carpet tube". That's the cardboard center of a roll of carpet. You can get this for free from any store that sells carpet. Just go look near their dumpster, or if you're feeling slightly ambitious you could ask a salesman.
   
4. An audio recording program. I recommend Audacity. Really any audio recording program that will show you a sonogram will work. Note: I've tried Garage Band on my MacBook, but I can't zoom in enough to see the required detail to make this work.