First of all, you can use this DEUS menu to choose between the 2, 3 or 4 tones modes. Then if you wish, you can precisely adjust the sound frequency of each tone (from low to high). DEUS can also determine which segment of the target conductivity scale each tone corresponds to.
The main advantage of this flexibility is convenience for any users with their own preferences or habits concerning sounds. It is also interesting for anyone who enjoys experimenting and structuring their search methods. And it is particularly useful for any users with partial hearing, for instance, who may be able to hear some sounds but not others.
In any case, a detailed knowledge of these Expert modes is not at all necessary for successful detecting, as the basic functions and programmes are already sufficient.