Which of the following statements are correct about sound? Choose the correct answer from the options given below.

1.An increase of 10 decibels (dB) is equivalent to a 10-fold increase in the intensity of sound.

2.An increase of 20 dB is equivalent to a 20-fold increase in the intensity of sound.

3.Loudness is the human perception of the intensity of sound.

4.The range of audible sound is between 20 Hz and 20 kHz.

5.Sound below 20 Hz is called ultrasound, while sound above 20 kHz is called infrasound.

A1, 2, 4 only

B2, 3, 4 only

C3, 4, 5 only

D1, 3, 4 only ✓ Correct

Correct answer: (D) 1, 3, 4 only

Explanation

On the decibel scale every 10 dB rise multiplies sound intensity ten times, so Statement 1 is right.

Statement 2 is wrong because a 20 dB rise means a hundredfold, not twentyfold, increase in intensity.

Statement 3 is right as loudness is the human perception of that intensity.

Statement 4 is right since the audible range runs from 20 Hz to 20 kHz.

Statement 5 is wrong because below 20 Hz is infrasound and above 20 kHz is ultrasound, the reverse of what it states.

The decibel scale is logarithmic, which is why small number changes mean large intensity jumps.

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