How does distance reduce noise level ?
Chloé at the concert
It is often mentioned in textbooks that the sound decreases with the square of the distance, but few experiments allow this to be verified. In this protocol, the student uses the sound of white noise from the sound library which achieves very stable and precise results. The activity opens up discussions on the risks of noise for health and the irremediable consequences for the body of a sound trauma.
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Sample protocol for the student
1. A friend of Chloe told her that the sound power produced by a speaker is 3 times louder at a distance of 1m than at 3m. Help Chloe verify this statement
2. On your laptop, in the Tool tab of FizziQ, find the White Noise sound in the sound library
3. On a second smartphone, select the Noise Level measurement
4. Place the two smartphones 20 cm apart from each other and measure the noise level
5. Now place the two smartphones at 3 times the distance and measure the noise level again.
6. What increase do you see?
7. An increase in sound level of 8 decibels is equivalent to a sound power multiplication by 9. Is Chloe's friend right?
8. After this analysis, do you think it is reasonable to stand near a speaker in a concert?
9. What minimum distance do you recommend to protect your ears?
11. Document your hypotheses, experiences and conclusions in the workbook and share it
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