An application processor is provided. The application processor includes a system bus, a host processor, a voice trigger system, and an interrupt pad. The host processor is electrically connected to the system bus. The voice trigger system is electrically connected to the system bus and performs a voice trigger operation and issues a trigger event based on a trigger input signal that is provided through a trigger interface. The interrupt pad receives a first interrupt signal in response to an operating environment changing from a low noise environment to a noisy environment, and a part of the voice trigger system is changed from an idle state to a normal state to perform the voice trigger operation in response to the first interrupt signal being received.