Final answer:
Pressing the ATT REV switch on an aircraft's audio control panel allows pilots to reverse the intercom system to the previous mode, prioritizing certain communications, such as reverting from external to internal communications as necessary.
Step-by-step explanation:
When you press the ATT REV (Attention Reverse) switch, you are typically interacting with a feature found on commercial aircrafts' audio control panels. This switch is used by pilots to quickly reverse the intercom system to the previous mode of operation or to prioritize certain communications. For example, if the crew is listening to communications from air traffic control and the ATT REV switch is pressed, it would allow the pilots to revert to intra-cockpit or cabin communication, effectively putting external communications on hold if need be. The ATT REV function ensures pilots can manage communications efficiently, focusing on critical information as flying conditions demand.