Mplayer and aplay together

OpenSuse 11.4 64bit KDE - I play radio streams using mplayer with pulseaudio activated. I would like to use aplay to play a time alarm, but I get the following error…

ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) unable to open slave
aplay: main:660: audio open error: Device or resource busy

How can I work around this using the Pulse Audio Volume Control.