What term refers to areas where air molecules are spread out in sound waves?

The correct term for areas where air molecules are spread out in sound waves is rarefactions. In the context of sound waves, which are longitudinal waves, compressions occur when air molecules are pushed together, creating areas of higher pressure. Conversely, rarefactions are regions where those same molecules are spread apart, leading to areas of lower pressure in the wave. This alternation between compressions and rarefactions allows sound to travel through the medium. Understanding this concept is crucial for grasping how sound waves propagate and interact with their environment.