Question

In order to reduce the loudness of a sound, we have to

• A. Decrease its frequency of vibration of the sound
• B. Increase its frequency of vibration of the sound.
• C. Decrease its amplitude of vibration of the sound
• D. Increase its amplitude of vibration of the sound.

Answer 1

The correct option is C

Decrease its amplitude of vibration of the sound

Explanation for the correct option

Option (C)

1. Sound is a longitudinal wave and it is one type of energy.
2. The loudness of sound or sound intensity is proportional to the square of the amplitude, i.e, $I\propto A^2$, where A is the amplitude of the sound wave and I is the intensity.
3. From $I\propto A^2$, it is clear that if we decrease the amplitude of the sound wave, then the loudness will decrease.

Explanation for incorrect options

Option (A)

1. The loudness of sound depends on the amplitudes, not on the frequency.

Option (B)

1. The loudness of sound depends on the amplitudes, not on the frequency.

Option (D)

1. As we know that sound intensity is proportional to the square of the amplitude, i.e, $I\propto A^2$.
2. Increasement in amplitude will increase the loudness of the sound.

Hence, option (C) is correct.