In some scenarios, such as test and application development, you may need to emulate a sound card in the VM (virtual machine). In Hyper-V there is no way to emulate a sound card. To use a "virtual
sound card" in a VM, you must enable audio over RDP (Remote Desktop Protocol) on Windows server 2008 or 2008 R2 host system. When you connect to the VM using RDP you can then run an audio program on the VM and have the sound redirected to the local computer.
To configure audio for all Windows applications over RDP:
If this does not work, check with your IT Administrator to see if there is a An Active Directory group policy in effect that disables Audio and Video redirection over RDP. Ask the administrator to remove this policy for the target machine.
To see all policies in effect on the target machine, on the command line type:
gpresult /H c:\temp\gp.html