The Pitch Hold feature on the Explorer SE is a built-in feature of the Sovereigns and Excals...the threshold will actually take on and hold the tone of the last target encountered, so that the pitch of the threshold elevates and stays there until it takes on the pitch of the next target encountered.
The way this is a help is that if you are one of those folks that uses the threshold the way it's intended to be used...to tip you off to those extra deep targets that might otherwise be missed completely, save for the fact that you LOST your threshold for a second. For example, let's say you are swinging along and you "catch the edge" of a DEEP target, like a worn Seated dime for instance...and your threshold cuts out for a half a second. You might assume that you went over some iron. Maybe you were going a little quick. Maybe your brain isn't as quick in hearing the little "tick" of high tone that was there for an instant but not good enough to may you go "Hmmm..." and you go right by it. But with Pitch Hold, you might notice the pitch of a silver coin as opposed to the pitch of iron and go "Huh...wait a minute!" and go back and have another look. Or another LISTEN, more like it. And lo and behold, at a closer look, from a better angle, you now have a broken but faintly repeatable "high and right" Smartfind or a shaky 00-29 signal at the limit of the depth meter.
That's how it works. Not for every hunter in every situation, but may have it's time and place. Probably NOT the hot ticket for a trashy location but maybe good if you're trying to cover some ground in a field or pasture.