I had a user running RHEL6 who no longer had sound. His computer has an Asus P8H67-M PRO motherboard. This board has a built-in Intel soundcard.

# lspci|grep Audio
00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 05)

After much screwing around, I found that the modules I needed to install were kmod-snd-hda and kmod-snd_hda. I’m not sure about the difference between these, but I put them both on. When I tried to install with yum, they also had a dependency on an older kernel.

# yum install kmod-snd-hda kmod-snd_hda
...
Dependencies Resolved

===================================================================================================================
 Package                Arch             Version                        Repository                            Size
===================================================================================================================
Installing:
 kmod-snd-hda           x86_64           1.0-1.el6_0                    rhel-x86_64-workstation-6            1.1 M
 kmod-snd_hda           x86_64           1.0.21.6.3.0-1.el6_2           rhel-x86_64-workstation-6            1.4 M
Removing:
 kernel                 x86_64           2.6.32-573.3.1.el6             @rhel-x86_64-workstation-6           126 M
Installing for dependencies:
 kernel                 x86_64           2.6.32-504.30.3.el6            rhel-x86_64-workstation-6             29 M

Transaction Summary
===================================================================================================================
Install       3 Package(s)
Remove        1 Package(s)

Total size: 32 M
Is this ok [y/N]:

Since I was currently using the kernel it wanted to uninstall, I reboot and picked a different kernel. Then, I just manually installed kernel 2.6.32-504.30.3.el6. I reboot again, into the 2.6.32-504.30.3 kernel and then installed the kmod-snd-hda and kmod-snd_hda packages. This took a while and I got a lot of warnings. But after a reboot, sound worked fine.

According to the RedHat page,
“This package provides the snd-hda kernel modules built for
the Linux kernel 2.6.32-71.18.2.el6.x86_64 for the x86_64
family of processors.”

So I should probably not upgrade the kernel on this computer if I want sound to continue to work.