It is an application program that confirms the right and left of the headphone.
The sound of feep becomes from a right headphone (The left is silent).
The headphone (earphone) as which right and left shape is the same
It is necessary to confirm the character printed in the headphone and to install it.
If this application program is used, the right and left can be easily distinguished even if the headphone is not seen.
When the headphone is not connected, the sound doesn't become it.
The warning display is done when the volume is small.