Considering a point source of sound wave and rarefactions forward in all direction with same velocity. So, the logitudinal waves due to the source propagates in spherical symmetry that is in all direction. The formation of wavefront is in accordance with Huygen's principle.


On a surface of sphere there will be either compression or rarefaction and that part can also behave like a source of sound but with low intensity.
Hence, Huygen's principle is valid for longitudinal sound waves also.