  The polarized Raman spectra of stoichiometric LaTiO$_3$ (T$_N = 150$ K) were
measured between 6 and 300 K. In contrast to earlier report on half-metallic
LaTiO$_{3.02}$, neither strong background scattering, nor Fano shape of the
Raman lines was observed. The high frequency phonon line at 655 cm$^{-1}$
exhibits anomalous softening below T$_N$: a signature for structural
rearrangement. The assignment of the Raman lines was done by comparison to the
calculations of lattice dynamics and the nature of structural changes upon
magnetic ordering are discussed. The broad Raman band, which appears in the
antiferromagnetic phase, is assigned to two-magnon scattering. The estimated
superexchange constant $J = 15.4\pm0.5$ meV is in excellent agreement with the
result of neutron scattering studies.
