Right...they're called comparators, and there's several types...
The simplest comparators look for incoming CV levels which cross a reference voltage level, and when the incoming voltage is either over or under the reference (depending on how you have it programmed), it can send either a gate or trigger. The trigger types tend to fire when the reference is crossed (and this can be upward or downward...but this sort of comparator is also known as a discriminator, as it can also tell whether an incoming voltage is moving upward, downward, or sometimes steady when the reference gets crossed), and gates tend to hold as long as the incoming CV is in the voltage range the comparator was programmed to look for.
But then...there are WINDOW comparators. Now, these are whole 'nother level of fun. What these do is to have (at least) TWO reference levels, so that you can fire a gate in ALL voltage ranges...above the top, between the two (or more) references, or below the bottom. You can also tandem these with triggering-type comparators that also send a trigger on reference crossings, too. For things such as generative music, these are super-useful for reading long voltage curves to change the "state" of the piece with the differing trigger/gate outputs.
But those are a little much for this sort of application. Let's see if I can insert a pic here...
https://www.modulargrid.net/e/emw-voltage-comparators
Did it work? If not, just go there. Anyway, this is a bank of four ultra-simple comparators...input, reference level set by a knob, and gate output. You'd then just patch channel 3 out of the 2s to this via a mult, then have it read for anything above X voltage, so that when your pitch exceeds a certain frequency, you get a gate. Easy-peasy.
Incidentally, I don't use ANY Eurorack comparators. I have something far more killer...biomed dual window comparators, with two voltage crossing triggers, three voltage-dependent gates, and one duration-dependent gate per channel, all outputted on Dupont pins, plus a four channel MUX. When you know your "abuse potentials", you can find crap like that...