There are wifi-based systems (like Sennheiser MobileConnect or Williams WAVECast), and my experience has been universally awful. The latency is so high that if you have any ambient hearing you get an echo that makes sound impossible to understand.
If you're ever considering installing one of these systems, please think again. Or at least trial it with a real situation, so you know what the experience will be like for the users.
If you're ever considering installing one of these systems, please think again. Or at least trial it with a real situation, so you know what the experience will be like for the users.