During an emergency it's important that messages can be sent and received from the intercom station where someone is requesting assistance. The time to find out that something is wrong with the intercom is not at that time. In the video below, watch how the Commend intercom system performs a self-test.
To ensure the constant availability of Intercom stations and Public Address loudspeakers, only an acoustic test can verify with certainty that everything is working correctly. Commend systems perform this test automatically and without any annoying sounds. Commend louspeaker-microphone monitoring is an actual acoustic test routine, which constantly checks the Intercom station’s signal path. It does so by emitting an audio test signal through the loudspeaker, which is picked up and analyzed by the microphone. The Intercom station then compares the transmitted signal against the received one to detect possible differences. In case one of the two components is not working correctly (e. g., due to chewing gum blocking the microphone or a loudspeaker membrane being damaged), the Intercom station will notify the control desk accordingly.
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