Between the special rooms (eg .anechoic room, reverberation chamber) and the corresponding controlroom there's a number of electrical connections so that's possible to send and receive signals to/from equipment located in the special room.

In this way its possible to have all unnecessary equipment removed from the special room and only keep absolutely needed equipment in the special room. In this way there's no equipment to disturb meaurements or human subject participating in listening experiment and then it's hopefully easier to test/measure single parameters.