The areas in a sound wave are called rarefactions. a. period b. frequency c. energy d. density

You can picture a sound wave a lot like a Slinky wave . . . a
thicker, compressed blob moving along the path, with thinner,
stretched-out places before and after it.

The thicker parts of a sound wave, where the air is more dense,
are called compressions.

The thinner parts of a sound wave, where the air is less dense,
are called rarefactions.