What can I use to test the difference between the sounds in different particles it's traveling through?I need .Sound Detector help for a project in which I test to see if sound will sound...

What can I use to test the difference between the sounds in different particles it's traveling through?

I need .Sound Detector help for a project in which I test to see if sound will sound differently in different particles it's traveling through.  An example would be if I test a 20 decibel sound in a pure hydrogen enclosure compared to the same 20 decibel sound in a pure oxygen enclosure.  I am just not sure what I could use to test the difference between the sounds.

Expert Answers
kjcdb8er eNotes educator| Certified Educator

This would be a great science project. What you will need is:

two small microphones (you could harvest them from any number of sources; a trip to your local thrift store is likely to net you discarded electronics with microphones. It would be best if they were identical, but this is not absolutely necessary.)

A noisemaker. This could be, for example, a small speaker that plugs into a laptop.

Multiplex the two microphones so that they both feed into a single stereo jack. Make sure that the wire lengths are the same for both Set up the experiment to that both microphones are in your environment and are separated by a known distance L.

Create your environment. I would use some sort of rubber tube where you can place the microphones/speaker inside (isolate them from external noise), and seal it off to contain the gas. If you use something hard like plastic or glass, remember that the sound will travel faster along the length of your environment than it does in the gas inside.


To make your measurement, simply use an audio recording software like Audacity and record what happens after you emit a beep (make it as short as possible, and at a single frequency). You should see two corresponding peeks on the audio recording. The distance between these two peeks is your time measurement.

now you know a = L/t, the speed of sound.


some tips:

1) don't use hydrogen. You can't get it, and it explodes. You could use helium instead; it's plentiful and fun.

2) don't use oxygen. You might be able to get it, but it can burn violently. use air instead; it's plentiful and lets you breath. Or, nitrogen if you can find some.

3) Don't rule out liquids or solids. You can set up a tube filled with water, jello, or even a solid glass rod.

4) Be prepared to interpret your results. Remember that there are many pathways for sound to get from from the buzzer to the microphones. You have to deal with echos, also. Do the math, know what to expect, and use that to help interpret your results.

5) Set up an audio filter. If your beep is at a single frequency, you can set up your audio software to exclude everything but that frequency. This would help you demonstrate your experiment in a noisy environment, say at the science fair.

6) make your beep as short as you can.

7) make L long. The two peeks will blend together if your beep is not short enough or L is too short. If your tube is coil-able, you can get really long lengths into a small volume.

8) there are easy ways to get the audio data into excel. If you look into it, you can make some nice charts. But the audio signal will probably be sufficient for your needs.


Good Luck!

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