  Sc3Mn3Al7Si5 is a correlated metal in which the Mn moments form a kagome
lattice that can frustrate magnetic interactions and no magnetic order develops
to the lowest measured temperatures. We have studied the phonon density of
states (DOS) in Sc3Mn3Al7Si5 using both inelastic neutron scattering (INS)
measurements and ab initio calculations. Above 10 meV, the INS data are
dominated by phonon scattering, with peak positions and intensities well
described by ab initio simulations of the one-phonon DOS. This indicates phonon
anharmonicity is not significant in this material. The partial phonon DOS
calculation shows neutron scattering is mainly sensitive to Sc
({\sigma}_scatt=23.5 barn), while Mn ({\sigma}_scatt=2.15 barn) make only a
small contribution. The lattice component of the specific heat is estimated
from the measured phonon DOS, and excellent agreement with the measured
specific heat from 30 K to 300 K is found, including contributions from lattice
dilation and the Sommerfeld coefficient, which are linear in temperature.
