Polaroid Digital AIR 3D Use And Maintenance Manual page 170

Before use, turn the volume to a minimum.
To adjust the volume use your finger to
rotate the small wheel:
rotate counterclockwise to decrease the
volume, clockwise to increase it .
Verify the functioning of the device by
placing it between two hands closed: if the
device is working properly it will produce a
sound/whistle (Larsen effect).
Volume
adjustment
170