  Hyperbolic crystals like {\alpha}-MoO$_3$ can support large wavevectors and
photon density as compared to the commonly used dielectric crystals, which
makes them a highly desirable platform for compact photonic devices. The
extreme anisotropy of the dielectric constant in these crystals is intricately
linked with the anisotropic character of the phonons, which along with photon
confinement leads to the rich physics of phonon polaritons. However, the chiral
nature of phonons in these hyperbolic crystals have not been studied in detail.
In this study, we report our observations of helicity selective Raman
scattering from flakes of {\alpha}-MoO$_3$. Both helicity-preserving and
helicity-reversing Raman scattering are observed. We observe that helical
selectivity is largely governed by the underlying crystal symmetry. This study
shed light on the chiral character of the high symmetry phonons in these
hyperbolic crystals. It paves the way for exploiting proposed schemes of
coupling chiral phonon modes into propagating surface plasmon polaritons and
for compact photonic circuits based on helical polarized light.
