For a sintered YBa2Cu3O7 sample that shows high far-infrared reflectivity we determined, by a Kramers-Kronig analysis, the dynamical conductivity and extracted contributions by free charge carriers and phonons. The low temperature conductivity, and also results of a tunnel experiment, can be described by a distribution of energy gaps around 2Δ/kTc reverse similar, equals 4.6. Furthermore we present evidence for superconducting fluctuations and we show that the lowest-frequency infrared-active phonon mode is less damped in the superconducting state than in the normal state.