I have created a virtual machine (VM), but I am unable to hear any sound from Rhythm box or Movie Player. The VM has the following parameters;

OS Type: Linux
Version: RHEL 6
hypervisor: kvm, x86-64

(When the VM was installed I unintentionally updated it to SL6.1 instead of keeping it at SL6.0)

$ uname -a
Linux localhost.localdomain 2.6.32-131.17.1.el6.x86_64 #1 SMP Wed Oct 5 17:19:54 CDT 2011 x86_64 x86_64 x86_64 GNU/Linux

$ cat /etc/redhat-release
Scientific Linux release 6.1 (Carbon)

Virtual hardware details (each individually tried);
sound: ich6
sound: es1370
sound: ac97

I have configured the VM to use each of the three virtual hardware sound options available, but sound is still inaudible.

Any ideas appreciated.