Figure 2-1.

The measured acoustic pressure of a wave traveling in the positive x direction. The curve shows the acoustic pressure as it varies in time at a fixed position or, equivalently, the variation in pressure with position at a fixed time. The wave exhibits distortion due to nonlinear propagation in water, resulting in the generation of harmonics of the transmitted frequency and an asymmetric waveform, i.e., a waveform with p⁺ > p⁻.