I heartily agree with digger,, The hum is easy to get used too and a slight change is noticible,, if the target is deep enough the detector cannot even tell if its silver or iron, but you can decide if you want to dig it because you know it's there. FYI I have found coins because of this,, My xlt seems to discriminate a little better when I swing it faster(when target is deep) so I hear a change, swing it a little faster, check the depth and then decide. Good luck!