Threshold / Adjusting The Background Audio Level - Minelab GPX 5000 Instruction Manual

Threshold
Adjusting the background audio level.
Threshold is the constant audible background tone or 'hum'
produced by the detector. The Threshold is your reference
point and lets you know what the coil is sensing, whether it
may be a target, ground noise, or electrical interference, so it is
important to set the threshold so it can be heard.
The level of the Threshold should be set low, but still audible
and stable. Ideally it should be a smooth, gentle hum. If you
set it so that it can't be heard you may set other detector
settings incorrectly.
Small targets or large deep targets may not produce a distinct
target signal, but may cause only a small variation in the
Threshold. If the Threshold level is set too high or too low
these very small variations may not be heard.
Listening for a target signal with a high Threshold would be
like trying to hear a whisper within a crowded noisy room. A
high Threshold may also be uncomfortable to your hearing.
If the Threshold is set too low the target signal needs to be
loud enough to become audible. Therefore, very soft target
signals, from small or very deep targets, may not be heard.
It is important to reset the Threshold level as conditions
change. For example, your ears may adjust to the low levels
of audio after an hour or so, or the conditions may have
become windy.
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