Interruptions

Here is what you need to do:

Go to the individuals who are making the announcements and respectfully share that their interruptions compromise your patient care.  Explain to them that you plan your sessions around their activites and appreciate the ways they improve the clients' quality of life while they are at the facility.  But that their announcement serve as a distraction, making it difficult for the patients to get the most from the therapy session.  If they continue to interrupt, you get a little tougher and explain that it is no different than if you interrupte their movie or sermon - on a second conversation, you get to be that blunt.

Most people are truly trying to be helpful and don't realize the harmful side effects of their actions.  If you gently explain to them how they aren't being helpful, they'll likely stop.  

None of us are mind readers.  We can't be held accountable for continuing annoying practices if noone has told us we are being annoying.  Tell them.

You might also suggest an alternate way of notifying them...perhaps they could post a sign in the therapy room.  Brainstorm with other therapists any suggestions you might be able to offer the other acitivities as alternate ways to keep patients apprised of events.

I try to bring an option to the table.  Even if your option isn't one they like, it makes your complaint more valid when you have put time into trying to come up with a solution and aren't just whining about what you don't like (not that you'd be whining, just a figure of speech around my house - says the lady with four kids!).