Answer: acoustic power
Explanation: A sound wave is a mechanical wave, so the energy is related to the intensity and the frequency of the same. The rate of "sound energy" as a function of time is called the "sound power" or "acoustic power" which is the rate at which sound energy is emitted or received.
If the acoustic power increases in a given point in space, this means that the point is receiving more sound energy, and then the loudness of the sound also increases at that point.