Final answer:
The 'push to talk' and 'release to listen' model of communication used by an EMT is known as half-duplex communication, seen in two-way radios and walkie-talkies.
Step-by-step explanation:
The model of communication that requires an EMT to 'push to talk' and 'release to listen' is referred to as half-duplex communication. This method is commonly used in two-way radios and walkie-talkies where the communication channel is shared. To talk, an individual needs to press a button (push to talk), and to listen, they release the button (release to listen), preventing the ability to simultaneously send and receive audio. This is a common practice in various emergency services, including police, fire, and emergency medical services, where clear and concise communication is crucial.