Metal detectors identify targets through audio, meters, lights, and or vibrations depending on the specific unit. The two most common methods are audio tones and digital or analog meters. Each of these metal detector identification features has its strengths and in some cases a metal detector will utilize both types of target id systems.
Metal detectors with audio identification systems often provide multiple tones that reflect the conductivity or size of the detected object. With audio id a detectorist does not need to repeatedly look at a display to decide whether or not to dig the signal. Because detectorists who rely on tone id spend a great deal of time listening to what the metal detector is reporting to them through sounds, he or she can often learn to distinguish various characteristics of an object such as shape, depth, and type of object by the way the audio responds. This is more difficult for new detectorists who have a metal detector with a visual display as it is easy to ignore sounds and rely solely on the display for guidance.
Metal detectors with a digital or analog meter display are helpful, because visual ids have a lower learning curve and seem to make the dig or no dig decision easier because the meter will display a number or symbol to the object. While this can make the choice to dig seem easier, it is important to remember that even the best metal detector id systems are fallible. For example, a piece of trash and a coin in close proximity to each other can create a situation where the metal detector averages their characteristics, presenting a target id that is not accurate for either target.
For this reason it is important to never fully trust any metal detector discrimination system as you may end up losing some valuable finds. However, in really trashy locations, it is often worth it to pass up a few misidentified targets, than it is to dig a ton of trash items.
Metal detector discrimination is a feature that allows the detectorist to receive signals that fall into a desirable identification range and ignore those targets whose characteristics suggest an unwanted object. Like id features, metal detector discrimination systems can be fooled, resulting in some valuable objects being missed. In areas with minimal trash, it is often rewarding to dig both good and bad signals alike. In a trashy area, however, a metal detector with a good discrimination system can reduce mental fatigue that comes from non-stop beeping.