Metal detectors have audio sounds also known as tones. These tones become audible when the detector passes over either a ferrous or non-ferrous target.
The Basics
Tone pitch is based on target conductivity
Low Tones
Indicate ferrous targets such as iron or low conductive objects such as nails and aluminum foil. These are often junk items, but some users specifically search for iron targets such as meteorites, historical tools, or medieval weapons like swords.
High Tones
Indicate non-ferrous targets or items with high conductivity such as gold jewelry or silver coins.
Sound
The target could be large or it may be close to the surface.
The target could be small or located very deep in the ground.
Tone Types
Mono Tones
All targets produce the same sound. When the detector is set in all-metal mode and there is no discrimination. In this case it will not be possible to distinguish at all which type of metal the detector signals under the ground. This can be particularly hard on contaminated sites.
Dual Tones
High tones for non-ferrous and low tones for iron.
Multi-tones
Different type of metals produce a different sound according to their conductivity.
Nexus Metal Detectors
