\begin{abstract}
The full set of hydrodynamic equations governing the pulsation 
of a sonoluminescing (SL) bubble is solved numerically taking 
ionization into account. We find that the hydro-thermal processes 
in an SL bubble are dominated by the formation of compression waves 
and up to 27\% of first-level ionization. The ionized core is
optically opaque, and the modified emitted light
power and pulse widths, as well as their wavelength dependence, 
are in excellent agreement with experimental data. 
\end{abstract}