So for people who haven't heard it turns out that Echolocation is a skill humans can learn and teach. That sounds like something that would be useful to adventurers.
From what I've gathered: There's passive echolocation that uses ambient noise. There's active echolocation where the user relys on things like clicking their tongue or tapping their feet.
Now for a starting point we have the level 1 Awakened Animal ancestry feat Natural Senses that grants 10 feet of Precise Echolocation as an option. As well as the level 5 Beastkin ancestry feat Greater Animal Senses that grants 30 feet of Imprecise Echolocation. Finally we have the human Ancestry Feats General Training and Advanced General Training that imply General Feats and Ancestry Feats are considered roughly equivalent in power.
So the Homebrew seems fairly straightforward.
Basic Echolocation General Feat 1
Gain echolocation 20 feet as an imprecise sense
Advanced Echolocation General Feat 3 (Would 7 with an upgrade be better?)
Enhance the echolocation you gained from Basic Echolocation to Precise
This splits the difference between the two existing Ancestry Feats.
Given the precedent of giving Deaf Characters the Sign Language Skill Feat for free it would make sense to be able to have echolocation as a blind character from level 1. Something like: As an optional rule if your character is Permanently Blind at level 1 they can take Basic Echolocation for free and have the option of trading their level 1 ancestry feat for Advanced Echolocation as well.
The real world version of this uses human audible sound unlike say a bat's ultrasonic echolocation and is a conciously used skill. Giving it a Concentration Free Action to turn on and a penalty to stealth checks would likely fit. But would that be too fiddily or make the feats too weak?
Other opinions?
Sources:
Also I remember in the mid 2000s to early 2010s there was a story about an ATV racer who could use passive echolocation from his and competitor's engine noise so well he could use it to race at over a hundred miles an hour. Implying that yes if you get good enough it can be predcise and fast enough to use in combat. But I can't find it. Anybody have any better luck with Google?