Question

As we move away from the source along with the amplitude which of the following quantity decreases as well ?

• A. waveform
• B. loudness
• C. wavelength
• D. intensity

Answer 1

Answer: (B)

loudness

The intensity or loudness of a sound depends upon the extent to which the sounding body vibrates, i.e., the amplitude of vibration. A sound is louder as the amplitude of vibration is greater, and the intensity decreases as the distance from the source increases. Loudness is measured in units called decibels.
Loudness depends on the square of the amplitude of the wave. That is, $loudness{\propto \left(amplitude\right)}^2$.
Hence, As it moves away from the source its amplitude as well as its loudness decreases.