  Polarized Raman scattering and infrared reflection spectra of hexagonal
HoMnO$_3$ single crystals in the temperature range 10-300 K are reported.
Group-theoretical analysis is performed and scattering selection rules for the
second order scattering processes are presented. Based on the results of
lattice dynamics calculations, performed within the shell model, the observed
lines in the spectra are assigned to definite lattice vibrations. The magnetic
ordering of Mn ions, which occurs below T$_N$=76 K, is shown to effect both
Raman- and infrared-active phonons, which modulate Mn-O-Mn bonds and,
consequently, Mn exchange interaction.
