Day 170: Sound Volume vs. Distance for 2 Different Media

College-Prep Physics: A student project examining how volume varies with distance. Is it inverse square like light and gravity? Is it different in different media? The student used a Casio keyboard to play a sustained note and used a Vernier sound meter to measure decibel levels at various distances. To test a different medium, the student used to cups connected by string, and used various length of string between the cups.

The sound using the cups and string was always louder than in air at the same distance, but it didn’t drop off in the same way as in air. We wonder whether the tension in the string might have something to do with it. Our reasoning being, if the string is more taught, the sound travels faster through the string and reaches the end with less decrease in amplitude, and therefore would sound louder. It is likely that the tension in string wasn’t held constant for different length string.


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About Frank Noschese

HS Physics Teacher constantly questioning my teaching.

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