What physical quantity determines the intensity of a sound beam?

The intensity of a sound beam is primarily determined by its power. In the context of sound waves, intensity is defined as the amount of energy that passes through a specific area over a certain amount of time. Power relates to this concept because it quantifies the total energy being emitted from the sound source per unit time. As power increases, so does the intensity of the sound beam, meaning a more powerful sound will carry more energy and be perceived as louder.

While frequency and wavelength are essential properties of sound, they do not directly define how much energy the beam carries through a given area; they instead describe the pitch and characteristics of the sound. Amplitude, on the other hand, is a measure of the maximum displacement of particles in the medium caused by the sound wave, and while it affects the loudness perceived by the listener, it does not measure the overall power of the sound beam. Therefore, power is the key factor influencing intensity.