Varying which of the following wave characteristics will cause the length of sound waves to vary?

The length of sound waves is determined by their wavelength, which refers to the distance between successive crests or troughs of the wave. When the frequency of a sound wave changes while maintaining the speed of sound in the medium, the wavelength alters inversely. This means that as the frequency increases, the wavelength decreases, and vice versa.

This relationship is described by the formula:

[ \text{Wavelength} = \frac{\text{Velocity}}{\text{Frequency}} ]

If the speed of sound is constant (which it typically is in a given medium at a certain temperature and pressure), any change in frequency directly impacts the wavelength.

In contrast, amplitude refers to the wave's height and relates to its loudness, while pressure does not influence the length of the sound wave directly. Although changes in amplitude and pressure will affect other characteristics of sound, they do not affect the wavelength. Thus, focusing on wavelength as the factor that changes the length of sound waves directly aligns with fundamental wave principles.