  We present results of reflectivity measurements with E parallel to c and E
perpendicular to c on NdBa2Cu3Ox (Nd123) single crystals close to full oxygen
doping. Along the c-axis the optical conductivity shows a well developed
absorption band around 450 cm^-1 at all temperatures. The in-plane optical
properties are dominated by crystal-field excitations at low energies, a
prominent step at 400 cm^-1 and a weaker feature between 500 - 550 cm^-1. A
comparison of the c-axis optical conductivity and the in-plane scattering rate
with neutron scattering derived spin susceptibility spectra suggests that the
in-plane and out-of-plane anomalies are caused by the same mechanism, probably
electron--spin scattering.
