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A hearing test is conducted on an aged p...

A hearing test is conducted on an aged person. It is found that her threshold of hearing is 20 decibels at 1 kHz and it rises linearly with frequency to 60 decibels at 9 kHz. The minimum intensity of sound that the person can hear at 5 kHz is-

A

10 times than that at 1 kHz

B

100 times than that at 1 kHz

C

0.5 times than that 9 kHz

D

0.05 times than that at 9kHz

Text Solution

Verified by Experts

The correct Answer is:
B
`L=5f+15`
So `L=40dB` at `f=5kHz`
`40=20log"(l_(2))/(l_(1))impliesl_(2)=100l_(1)`.
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