Question

A person speaking normally produces a sound intensity of 40 dB at a distance of 1m.If the threshold intensity for reasonable audibility is 20 dB, the maximum distance at which he can be heard clearly is?

Answer 1

Given A person speaking normally produces a sound intensity of 40 dB at a distance of 1m.If the threshold intensity for reasonable audibility is 20 dB, the maximum distance at which he can be heard clearly is?

We know that I is proportional to 1 / r^2

So intensity varies with distance

I 1 / I2 = r2^2 / r1^2

Now 10 log 10 I1 / Io = 40 db

So I1 = Io x 10 ^4 w/m^2

  I2 = Io x 10^2 w/m^2

r1 = 1 m

r2^2 / 1^2 = 10^4 / 10^2

r2^2 = 100

r2 = 10 m

So maximum distance is 10 m

Answer 2

Answer:

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