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A sound absorber attenuates the sound level by 20 dB. The intensity decreases by a factor of

1. 100
2. 1000
3. 10000
4. 10

Correct answer: 100

Solution

Level drop = 10*log10(I0/I). 20 = 10*log10(ratio) -> ratio = 10^2 = 100. The intensity decreases by a factor of 100.

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