An input/output module comprising: an audio input device; an audio output device disposed at a distance from the audio input device; and a failure detection apparatus comprising: an output portion that outputs to the audio output device a confirmation signal that is a burst signal and is in a frequency band other than an audible band, wherein the confirmation signal: switches, during a period of the burst signal including a first section and a second section, from the first section to the second section, includes an envelope that gradually increases over time during the first section and gradually decreases over time during the second section, and has an arbitrary duty ratio of the first section to the period; an input portion that receives an input signal from the audio input device; and a failure detection portion that detects whether the audio output device and the audio input device are operating normally, characterized in that the failure detection portion detects whether the audio output device and the audio input device are operating normally based on a ratio of a time length of a third section of the burst signal and an entire time length of the period of the burst signal, wherein the third section includes the first section and a portion of the second section in which an amplitude thereof is equal to or greater than a predetermined threshold value. an audio input device; an audio output device disposed at a distance from the audio input device; and a failure detection apparatus comprising: an output portion that outputs to the audio output device a confirmation signal that is a burst signal and is in a frequency band other than an audible band, wherein the confirmation signal: switches, during a period of the burst signal including a first section and a second section, from the first section to the second section, includes an envelope that gradually increases over time during the first section and gradually decreases over time during the second section, and has an arbitrary duty ratio of the first section to the period; an input portion that receives an input signal from the audio input device; and a failure detection portion that detects whether the audio output device and the audio input device are operating normally, an output portion that outputs to the audio output device a confirmation signal that is a burst signal and is in a frequency band other than an audible band, wherein the confirmation signal: switches, during a period of the burst signal including a first section and a second section, from the first section to the second section, includes an envelope that gradually increases over time during the first section and gradually decreases over time during the second section, and has an arbitrary duty ratio of the first section to the period; switches, during a period of the burst signal including a first section and a second section, from the first section to the second section, includes an envelope that gradually increases over time during the first section and gradually decreases over time during the second section, and has an arbitrary duty ratio of the first section to the period; an input portion that receives an input signal from the audio input device; and a failure detection portion that detects whether the audio output device and the audio input device are operating normally, characterized in that the failure detection portion detects whether the audio output device and the audio input device are operating normally based on a ratio of a time length of a third section of the burst signal and an entire time length of the period of the burst signal, wherein the third section includes the first section and a portion of the second section in which an amplitude thereof is equal to or greater than a predetermined threshold value.