What term describes the maximum pressure variation in a sound wave?

Amplitude refers to the maximum pressure variation in a sound wave. It is a critical parameter in understanding sound waves, as amplitude is directly related to the loudness of the sound; higher amplitudes correspond to louder sounds, while lower amplitudes indicate softer sounds. In the context of sonography, the amplitude of the ultrasound wave affects the strength of the reflected signals received from tissues, influencing image quality and clarity.

Intensity, on the other hand, is related to the power of the wave over a specific area but does not directly describe the pressure variation itself. Frequency measures how many cycles occur in one second, which relates to pitch but not to the pressure changes in the wave. Speed refers to how fast the wave travels through a medium, which is separate from its pressure characteristics. Thus, amplitude is the correct term that accurately describes the maximum pressure variation in a sound wave.