The reciprocal of the damping rate in the classical Lorentz harmonic oscillator model is equal to the phonon lifetime due to the concept of dephasing. Without damping, an oscillator would continue indefinitely, but the damping rate indicates how quickly the oscillation is interrupted. In quantum mechanics, states experience dephasing, leading to a loss of coherence characterized by a specific lifetime. This loss of coherence ultimately results in the cessation of the oscillator's motion. Thus, the relationship between damping and phonon lifetime is rooted in the dynamics of coherence loss.