We present temperature- and field-dependent inelastic light-scattering studies of multiferroic ${\text{TbMnO}}_{3}$. By carefully examining the evolution of magneto-elastic modes in various phases of ${\text{TbMnO}}_{3}$, our study reveals several features of the field-induced incommensurate-commensurate (IC-C) transition in ${\text{TbMnO}}_{3}$. We find that, for fields applied along the $b$ axis, there is a coexistence of distinct structural phases in the intermediate field regime $(H=4--7\text{ }\text{T})$ around the IC-C-phase transition. We present evidence for the existence of dynamical fluctuations of the C phase for fields lower than the critical field for $\mathbf{H}$ along the $b$ axis, $H<{H}_{c}^{b}$. Furthermore, we present evidence for strong spin-lattice coupling effects in ${\text{TbMnO}}_{3}$ in the form of zone-boundary phonon modes that strongly couple to the spins by modulating the exchange interaction in this material.