In general, I think you are definitely right about this. Sound does have some potentially interesting applications. For example, if you had an exhibit that you

In general, I think you are definitely right about this. Sound does have some potentially interesting applications. For example, if you had an exhibit that you wanted guests to interact with, that would probably eliminate many wireless choices. NFC would be a valid option, but not all phones support it, and you might need to make the user install an app. Quiet's sound transmission can work from the browser by using quiet.js. In general I think it's ever so slightly more versatile, or at least until browsers make it easier to access wireless options.