Not Mute is the name of a counteradvantage.
http://www.sjgames.com/gurps/faq/FAQ4-3.html#SS3.2.16 mentions Fantasy has it
It is a way of someone with mute to regain speech. In it's raw form it should cost 25 points.
F134 prices it at 22 points because it is built to cancel out an aspect of the Unmanifested Spirit metatrait: Mute with the Substantial Only mitigator. This probably should have instead been called "Not Mute to Substantials" since Mute to Substantials effectively describes the limited version which those spirits have.
In this case the purpose is to permanently override the limited/mitigated disadvantage built into that template to effectively make it Astral Entity.
This is different than the later use of counteradvantages in PU8 which is intended for the TEMPORARY overriding of disadvantages.
Using the PU8 approach would actually involve removing the "Substantial Only" limitation from Mute as improper.
Instead the proper way to do it would be to apply Insubstantial Only to Not Mute. -30% from 25 is 17.5 which rounds up to 18 points. 18 minus 25 is merely a -7 point disadvantage, not -22 as before.
- one problem with this pricing though is that Insubstantial Only is actually a mixed trait: is basically Not Substantial -70% as a higher-value limitation placed atop B102's Affects Substantial's +40%. Someone already able to affect insubstantial targets (for example: nobody needs to buy "Affects Insubstantial" to be heard or seen by substantial targets, only to DAMAGE them) would not need the +40% so they should get a higher value for the "Not Substantial" component.
- -70% results in a 0.3*25=7.5 cost which rounds up to 8 points for the counteradvantage using this approach.
- 8-25 = -17 value for "can only be heard by insubstantial creatures", which is more generous, but still less than the -22 it was previously assigned
- -70% results in a 0.3*25=7.5 cost which rounds up to 8 points for the counteradvantage using this approach.
B263 uses Substantial Only as a limitation on Invisibility which is legal because you are normally invisible to insubstantial creatures too. This is also a somewhat-known trick to save points on things like Malediction which has Affects Insubstantial baked into it: the first tier is actually only a +60% enhancement when you subtract that.