I would have to check mine to be sure but am pretty sure it is about 5. I cut the threshold tone, variability and limits down all the way. Then adjust the limits on iron, nickles and silver for three tones. I then adjust variability and make sure I have a nice clear three tones. With them all the way down there is one then you hear two come in and then three and you adjust the limits up by a click at a time. With threshold tone at low as it can go then the threshold on the display set for a slight sound the threshold is in the background. Iron hits will have the sound of the threshold. With Audio gain at about 4 those sounds are not a bother but a higher tone will come through nice and clear. This stops all that banging that goes on and gets the sounds under control. With blanking it is very easy to work through heavy trash.
I like to use the Learn/Edit at a specific site so the ground minerals are included for that site and store that in an S slot. If you have followed it and worked through the setting you will now notice there are ICONS for trash in the clear area of the display to help ID them. With the open area at top left we now see Nail/Screw for 31/31 and 30/31. You can use conductive or ferrous sounds but ferrous makes more sense to me since it is the same as ferrous and non-ferrous instead of high conductive for both silver, a lot of iron and alloys.