I was gobsmacked when I learnt that humans are capable of using sonar, like bats. Even the meta-knowledge seems to have disappeared, strange. I've sometimes won

I was gobsmacked when I learnt that humans are capable of using sonar, like bats. Even the meta-knowledge seems to have disappeared, strange. I've sometimes wondered whether I could learn it, but I never got round to it, I guess there wouldn't be many courses anyway. But I urge anyone who has a visually impaired person in their family to look into this seriously - as with any skill, the sooner you pick it up the better.