What is measured in decibels (dB)?

The measurement in decibels (dB) is primarily associated with loudness, which refers to the perceived intensity of a sound. Loudness is not measured directly in terms of volume but rather how we perceive the strength of sound waves. The decibel scale quantifies sound levels in a logarithmic manner, where an increase of 10 dB represents a tenfold increase in sound intensity, which correlates with our perception of changes in loudness.

While sound waves themselves form the basis of sound, decibels specifically measure the intensity of these waves as perceived by a listener. Pitch and frequency deal with the characteristics of sound related to its tone and how high or low a sound is, but they are not quantified in decibels. Instead, pitch is often related to the frequency of a sound wave measured in hertz (Hz). Therefore, the decibel scale is fundamentally a measurement of loudness rather than the other aspects of sound.