Instructions
Check the headphone port on the DSi if no sound is coming from the speakers. Remove any device connected to the headphone port.
Make sure the headphone jack is fully inserted into the headphone port if no sound is coming from the headphones.
Adjust the volume control. The control to increase or decrease the volume are on the edge of the DSi to the left of the directional control pad. To increase the volume, press the "+" button; to decrease the volume, press the "-" button. The buttons control the volume for both the speakers and headphones.