Garrett Metal Detectors Metal Detectors GTAx 550 - Manual (Page 39)

HEADPHONE JACK
The headphone jack on the GTAx 550 is located at
the rear of the removable battery pack under the
armrest. Headphones are a valuable accessory
for any metal detector to mask interference from
outside noise. They permit you to hear small and
deep targets that might be missed when using only
audio from the detector speaker. Headphones are
particularly essential when you are hunting where
noise of people and/or traffic is excessive.