What measurement unit is used to quantify loudness or intensity of a sound?

The unit used to quantify loudness or intensity of a sound is decibels. This logarithmic unit measures the relative intensity of sounds, providing a way to express a wide range of sound pressures experienced in our environment, from the faintest whisper to a rock concert. The scale is convenient because it reflects how humans perceive changes in loudness; for example, an increase of 10 decibels is generally perceived as roughly twice as loud to the human ear.

Hertz, on the other hand, is a unit that measures frequency, indicating how many cycles of sound waves occur in one second, but does not indicate loudness. Pascals are used for measuring pressure, including sound pressure, but do not directly measure loudness or intensity in a way that corresponds to human perception. Decagrams measure mass, which is unrelated to sound intensity. Thus, decibels are the appropriate unit for quantifying loudness.