Consider the following statements regarding noise pollution. Choose the correct answer from the options given below:

1.Noise levels decrease as we move away from the source of noise

2.Materials with high surface/mass density act as good noise barriers

3.Sound pressure of 2µPa corresponds to zero decibel

A1 and 2 only ✓ Correct

B2 and 3 only

C1 and 3 only

D1, 2 and 3

Correct answer: (A) 1 and 2 only

Explanation

Statements 1 and 2 are correct: noise levels fall as one moves away from the source, and dense heavy materials make good noise barriers.

Statement 1 is right because sound energy spreads out and weakens with distance from its source.

Statement 2 is right since materials of high surface and mass density block and absorb sound well.

Statement 3 is wrong because the reference sound pressure for zero decibel is 20 micropascal, not 2 micropascal.

That 20 micropascal reference marks the faintest sound a healthy human ear can detect.

The decibel scale is logarithmic, so each ten unit rise means a tenfold increase in sound intensity.

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