Only option available is "no sound" on both user and ACP.
You'll need to also check out the 0.5.1 branch of the vanilla theme as well.
I thought this must be just one line or one function. I stared at the code and the database, and didn't get what's the point of the matter.
Sorry. I just could reproduce it, but didn't know why it works that way.
I previously had this issue. It only affects admins who have the rights to change the order of the pinned topics which is why it's unlikely others can't reproduce on the OPs site.
However since 1.7 (could be Chrome 64) I no longer have the problem.
👏 What a relief 😄
It was fixed, but the forum was not updated. Now is. Over and out.