The measure of the intensity of sound waves is called sound pressure level, typically expressed in decibels (dB). Sound waves are pressure fluctuations in a medium such as air, and their intensity relates to the amount of energy the waves carry. The decibel scale is logarithmic, meaning an increase of 10 dB represents a tenfold increase in intensity. Understanding sound pressure level is crucial in various applications, including acoustics, audio engineering, and environmental noise control.