Speaking of Acoustiguide, their product information does list “Remote triggering:
Optional Radio frequency systems” as an available feature. Other interesting tidbits from their site: Museums can purchase a data collection feature which allows them to download information from the units about what the user listened to (which translates to the route they took) and the related timing. “In general, men and younger visitors prefer headsets, and women prefer wands.” And if you’ve noticed that more museums are offering their audio tours for free, note that “Under this arrangement, all visitors are offered an audio program with a highly perceived value at a minimal cost to the client. The institution may raise the admission price marginally, and Acoustiguide is paid a per visitor fee.”