@zachdecook @sir Precise echo location imaging seems to be a rather rare trait, at least I heard blind folks talk about this ability in other blind people with a sense of marvel.

However, as any singing or speaking classes will teach, posture has an effect on sound, and gestures have an effect on posture.

So, hypothesis: Since language is picked up through emulation, blind people will notice that certain passages sound sharper than others and tweak their behavior to match until they end up with the lowest-effort technique to achieve that, and that's gestures.