  We present time-dependent dielectric loss data at different frequencies for a
variety of glass formers after cooling below the glass temperature. The
observed aging dynamics is described using a modified Kohlrausch-Williams-Watts
law, which takes into account the time-dependent variation of the relaxation
time during aging. It leads to values for the aging relaxation time and
stretching exponent that are fully consistent with the results from equilibrium
measurements performed at higher temperatures. Irrespective of the dynamic
process prevailing in the investigated frequency region, the aging dynamics is
always determined by the structural relaxation process.
