Standing waves are equal-amplitude counterpropagating traveling waves

Evidence

Equation 8.19 makes clear that a sinusoidal standing wave, described as a sinusoidal shape function sin knx multiplied by a sinusoidal time function sin 2πfnt, is in fact a sum of two counterpropagating sinusoidal traveling waves of equal amplitude. — Eric J. Heller, Why You Hear What You Hear- An…, 845

Categorization

• DEFINE: Clarifies the standing-wave equals opposing-traveling-waves equivalence, a key conceptual bridge in wave physics.