Which of the following is NOT a characteristic of sound diffusion?

Sound diffusion refers to the process in which sound waves scatter as they interact with surfaces and obstacles in an environment. The primary characteristics of sound diffusion include its ability to cause sound waves to bend, reflect, and be absorbed by various materials.

The bending of sound waves occurs as they encounter different surfaces or mediums, leading to changes in direction. Absorption of sound is another critical characteristic, where materials reduce sound energy through conversion into other forms of energy, ultimately diminishing the sound's intensity. Reflection involves sound waves bouncing off surfaces, which contributes to the acoustic environment and influences aspects such as reverberation and clarity of sound.

Sound speed variation, however, factors into the physics of sound itself, dictating how fast sound travels through different mediums but not defining diffusion. While variations in sound speed can affect how sound propagates, they do not describe the scattering or spreading behavior associated with diffusion. Therefore, identifying sound speed variation as not characteristic of sound diffusion is accurate, as it relates more to the mediums themselves rather than the behavior of the sound waves.