| 摘要 |
<p>When the instruction for increasing the volume level is input by the user's operation and the signal representing the set value or more is output from a detector, a controller does not increase the volume levels of the first volume controller and the second volume controller. When the signal representing the set value or more is not output from the detector and the second volume level has a predetermined value, the controller increases the first volume level. When the signal representing the set value or more is not output from the detector and the second volume level is less than the predetermined value, the controller increases the second volume level.</p> |
