However, the audio output apparatus 1 may be configured such that the rotating body 3 is rotatable in only one direction relative to the base body 2. In this case, the audio output apparatus 1 for the left ear 100 and the audio output apparatus 1 for the right ear 100 are identified in advance, and the audio output apparatus 1 for the left ear 100 is fitted in the left ear 100 by rotating the rotating body 3 in one direction relative to the base body 2, whereas the audio output apparatus 1 for the right ear 100 is fitted in the right ear 100 by rotating the rotating body 3 in the other direction relative to the base body 2.

<Other Examples of Audio Output Apparatus>

The foregoing has described the audio output apparatus 1 that includes the antenna by way of example. However, instead of the audio output apparatus 1, an audio output apparatus 1A having a configuration in which, for example, no antenna is disposed can be used (see FIGS. 21 and 22).

A cable 30 is connected to the audio output apparatus 1A and, via the cable 30, power is supplied to, and signals are transmitted to and from, the audio output apparatus 1A. In the audio output apparatus 1A, for example, the microphone 23 is placed inside the base body 2, the speaker 22 and a terminal portion 31 are placed inside the rotating body 3, and the cable 30 is connected to the terminal portion 31. The terminal portion 31 and the speaker 22, and the speaker 22 and the microphone 23 are connected by connection lines 26 and 26, respectively.