Comment 3 for bug 457144

Francesco, could you try to create an /etc/asound.conf file like the one here: http://pulseaudio.org/wiki/PerfectSetup#ALSAApplications
In terminal:
gksu gedit /etc/asound.conf

Then copy and paste the code below into the file. Save, quit, and reboot. See if alsa apps works properly now:
pcm.pulse {
    type pulse
}
ctl.pulse {
    type pulse
}
pcm.!default {
    type pulse
}
ctl.!default {
    type pulse
}