Hi Sbower,
Network port necessary for Parallels Access to establish connection to the remote computer is blocked or closed, hence no sound from the remote computer is transmitted to iPad.
Please follow the steps given :
To ensure the full connection quality please make sure the following network port is not blocked on both remote computer and Parallels Access sides:
443:TCP
To make sure sound can be heard through Parallels Access please make sure it is not turned off(
http://kb.parallels.com/116685).
Thanks,
Manoj D