Garrett Metal Detectors Metal Detector GTI 1500 - Manual (Page 33)

controls the maximum volume of sound
produced by the GTI 1500 only when a
target is encountered, it will not affect the
threshold level you have already selected
as the primary audio function of your
detector.
When headphones are used, it will usually
be necessary to decrease volume since
detections sounds are louder over head-
phones. Experiment to determine which
volume best suits your hearing.
Tone
After using the MENU touch pad to display
TONE on the screen, the factory tone set-
ting will be indicated on the Upper Scale,
as shown. Use the + and - touch pads to
adjust the audio to preferred pitch or tone.
Touching the + pad will raise the tone into
a higher treble range, while touching - will
Graphic Target Imaging 1500 -