  1$T$-TaSe$_2$ is a prototypical charge density wave (CDW) material for which
electron-phonon coupling and associated lattice distortion play an important
role in driving and stabilizing the CDW phase. Here, we investigate the lattice
dynamics of bulk 1$T$-TaSe$_2$ using angle-resolved ultralow wavenumber Raman
spectroscopy down to 10 cm$^{-1}$. Our high-resolution spectra allow us to
identify at least 27 Raman-active modes in the commensurate (CCDW) phase.
Contrary to other layered materials, we do not find evidence of interlayer
breathing or shear modes, suggestive of $AA$ stacking in the bulk, or
sufficiently weak interlayer coupling. Polarization dependence of the mode
intensities allows the assignment of their symmetry, which is supported by
first-principles calculations of the phonons for the bulk structure using
density functional theory. A detailed temperature dependence in the range $T$ =
80 - 500 K allows us to identify soft modes associated with the CDW
superlattice. Upon entering the incommensurate (ICCDW) phase above 473 K, we
observe a dramatic loss of resolution of all modes, and significant linewidth
broadening associated with a reduced phonon lifetime as the charge-order
becomes incommensurate with the lattice.
