Might the file /etc/asound.conf an issue?
With my previous OS (CentOS 5.6) this file looked like:
#Generated by system-config-soundcard, do not edit by hand
#SWCONF
#DEV 0
defaults.pcm.card 0
defaults.pcm.device 0
defaults.ctl.card 0
though in Fedora 17, this file is blank except for the comments:
#
# Place your global alsa-lib configuration here...
#
Also, in the past, with CentOS and other RedHat distributions,
I use to use the tool system-config-soundcard. It does
not appear that this tool is still available for Fedora17.
Thanks;