How do rough walls affect sound waves when they reflect?

Rough walls play a significant role in how sound waves behave upon reflection. When sound waves encounter a rough surface, they do not reflect in a single, directed manner. Instead, the irregularities and textures of the wall scatter the sound waves in multiple directions. This scattering effect is known as diffusion, which helps to break up the sound and spread it out over a wider area.

This diffusion can contribute to a more pleasant auditory environment, as it reduces the intensity of echoes and creates a more balanced sound field. In spaces with rough walls, listeners can experience a richer sound experience because the direct sound waves are mixed with the diffused reflections, preventing the extremes of echo or focused sound pathways.

The other options highlight different interactions of sound with surfaces that are not characteristic of rough walls. Smooth surfaces, for example, are more likely to create echoes or even focus sound pathways, while soft materials might absorb sound instead of reflecting it. Thus, the nature of rough walls specifically promotes the diffusion of sound waves in a variety of directions, making this option correct.