Thanks, tonyinmi. They try pretty hard to keep track of them, but it's hard to know if my mom is taking them out and leaving them somewhere outside of her room, or if other residents are coming in and taking them. All kinds of things go missing from her room and things that don't belong to her show up in her room. From what I understand, that's pretty common in these facilities.
I'll take a look at the Pocketalker. If nothing else, it may bridge the gap between when a hearing aid goes missing and is found.