2.10.1 Microphone Input on a Headset
As stated in the audio jack section of the Nintendo 3DS Overview, the Nintendo 3DS mini-jack port is compatible with microphone input.
However, as of August 2016, Nintendo does not manufacture a standard headset, and only few licensed models produced by another company are available. As a result, Nintendo does not recommend designing your application on the assumption the user has a headset.
No required guideline items.