A test module for functionally testing an audio device of an aircraft passenger service unit (PSU) is configured to allocate a first operating mode to a first individual audio device of one PSU of a set of PSUs during which, a test tone is emitted. The test module allocates a second operating mode to other audio devices different than the first audio device. In the second operating mode, the test tone emitted by the first audio device is intended to be received. The other audio devices each belong to different PSUs within the set of PSUs. The test module emits the test tone via the first audio device. The test module initiates a functional test of the first audio device. The functional test is based on the test tone received by the other audio devices. The test module may be part of a system and an aircraft.