What name is given to the study and control of signal emanations from electrical and electromagnetic equipment?

TEMPEST is actually a National Security Agency specification codename and NATO certification referring to spying on information systems through leaking emanations, including unintentional radio or electrical signals, sounds, and vibrations. it also encompasses sounds or mechanical vibrations. For example, It is possible to log a user’s keystrokes using the motion sensor inside smartphones. Compromising emissions are defined as unintentional intelligence-bearing signals which, if intercepted and analyzed, may disclose the information transmitted, received, handled, or otherwise processed by any information-processing equipment. (Wikipedia)