Did he have Music or Sound turned off? I know I always had the music turned off. There are also a lot of new filters in the Classic and Enhanced client now for filtering our sounds, not to mention he could have something clicked on his Assistant.
If you try with two accounts and still can not hear on both let me know.
As a side note I have no idea how these are supposed to work on UO.
I tried turning the music on, and leaving and coming back but still wasn't able to hear it. I just checked and I don't have any of the filters clicked on my assistant, and I don't think I have any clicked in the client (classic). It looked pretty sweet though