  We study the dipole-dipole spectral broadening of a resonance line at high
atomic densities when the self-broadening dominates. The selective reflection
spectrum of a weak probe beam from the interface of the cell window and
rubidium vapor are recorded in the presence of a far-detuned pump beam. The
excitation due to the pump reduces the self-broadening. We found that the
self-broadening reduction dependence on the pump power is atomic density
independent. These results provide experimental evidence for the disordered
exciton based theory of self-broadening, and can be useful for the description
of the interaction of a strong optical field with a dense resonance medium.
