Method for testing an audio communication system of an air-craft, and aircraft having an audio communication system

An aircraft having an audio communication system comprising:

• a jack having an audio output,
• a microphone input,
• a plug detector which is configured to generate an interrupt signal when a jack plug of a headset is plugged into the jack,
• a test bridge circuit, connected to the plug detector, which is configured to interrupt an electrical connection between the audio output and the microphone input when the plug detector generates an interrupt signal;
• an audio input connected to the audio output of the jack;
• a microphone output connected to the microphone input of the jack;
• and
• a signal processing apparatus connectable to the audio input and the microphone output;
• wherein the signal processing apparatus is configured to apply a test input signal to the audio input, to tap off a test output signal at the microphone output and to use the test output signal to ascertain a functional state of the audio communication system.