Sound intensity is determined by what?

• A. Amplitude of the sound wave
• B. Frequency
• C. Wavelength
• D. Phase

Answer: (A)

Sound intensity is the energy crossing a unit area each second. For a traveling sound wave, that energy flow grows with the square of the pressure (or displacement) amplitude. In other words, larger amplitude means more energy per second, so higher intensity. Frequency, wavelength, and phase describe other aspects of the wave—pitch, speed-related relationships, and the wave’s position in time or space—but they do not set the energy transfer rate by themselves.