I was trying some of the solutions published in this forum for the same problem, but just one in particular work for me: add the line of code in the file alsa-base.conf. This just works for a few days, now the problem is back again.
Any solution to fix this problem for good?
Compaq Presario CQ40
$ lspci | grep -i audio 00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA) 01:05.1 Audio device: ATI Technologies Inc RS780 Azalia controller