When a sound wave moves past a point in air, are there changes in the density of air at this point?

Yes

Explanation:

When a sound wave moves through the air, a point in the air undergoes alternative changes in density called compressions and rarefactions.

A sound wave is a longitudinal waves, which means that the vibrations of the particles in the medium occur in a direction parallel to the direction of motion of the wave. Longitudinal waves creates two different regions in the medium:

- Compressions: these are regions where the density of the particles of the medium (in this case, air particles) are higher

- Rarefactions: these are regions where the density of the particles of the medium (in this case, air particles) are lower