Speech Privacy on HC

Hello. There's another doubt now about Speech Privacy accoeding items 4.4 and 4.5 guide 2010 FGI, where comments Enclosed Rooms and Open-plan spaces. So, for Enclose Rooms what situations are applied? For example, between Patient room - Patient room? It really can be used "sum of the composite STC and A-weighted background noise level > 75? Because usually we adopt STI index and this value is simulated in open spaces. Usually what are the open environments (open-plan) to be simulated in hospitals? Preparation room for exams? Anesthetic recovery room? Administrative rooms? Thank you.