Question

The unit to measure the loudness of sound is called _______________.

Answer 1

1. Loudness is a subjective quantity and differs from person to person.
2. The loudness of sound is measured in $decibels\left(dB\right)$.
3. The minimum loudness of sound audible at a frequency$1kHz$ is considered to be the zero level of sound i.e,$0dB$.

Hence, the unit to measure the loudness of sound is called $decibels\left(dB\right)$.