Intensity ($I$) is the power delivered by a wave per unit area. For a harmonic wave: $I=\frac{1}{2}\rho v{\omega }^2{A}^2$ where:

• $\rho$: density of the medium
• $v$: wave speed
• $\omega$: angular frequency ($2\pi f$)
• $A$: amplitude The most important takeaway is $I\propto A^2$ and $I\propto f^2$. This scale relationship is fundamental to energy calculations for sound, light, and mechanical vibrations.