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Comment by alexvoda | Hacker News Reader

Fascinating.

I find it hard to imagine what learning such a skill entails.

If you can make a clicking noise with the side of your tongue, you can easily sense the volume of space you’re in, how close to a wall, etc.

I’ve read about this, but I’ve never understood what that means. I can click my tongue but I can never hear any kind of echo. Is it a very particular click?

You will not distinguish an echo, just a change in the "tone" of the sound you make as it reverberates in your surroundings.

The echo pulses are there but just milliseconds after the sound you made. It will all blur into a softer or harder reverb depending on your surroundings.

To hear an actual separate echo pulse, it would need to be 20-100 milliseconds later than the original sound. That corresponds to a large hall tens of meters in size.

Doing a loud clap with your palms aligned and as flat as possible produces an adequate sound.

Sharp and short, alternating left and right at about 4 Hz, on the side of the tongue back by the molars. Feels like pulling the side of the tongue away from the teeth. It’s a much clickier click than a front of the tongue ‘click’.

See the videos in my other comment. Daniel Kish explains how he does it.

I have practiced echolocation for fun. Getting some basic awareness from your surroundings is not that difficult, like detecting if there is a wall on your left or right side.

The difference in the sound response is subtle but clear. It's like tweaking the knobs of a reverb effect in an audio processing software.

It is not about detecting discrete echo pulses like a radar or a sonar does, it's about sensing a change in the "tone" of the sound you make.

In signal processing terms you're "measuring" the impulse response of the room around you.

Neural plasticity goes a long way.

Yeah, I find this almost unremarkable compared to the wide variety of other things humans already do. I think it's pretty obvious we don't have any specialized hardware for echo location like bats or dolphins do, but our brains are pretty big, and our hearing is actually quite good. We spend so much time talking about how this or that animal can hear ultrasonic sounds or whatever that we often end up with the idea that our hearing isn't very good, but even our base hardware is actually fairly good by animal kingdom standards, and it's hooked up to one heck of a brain on the backend. It's not surprising to me that we can bash together some echolocation with just the hardware we have and software we can learn.

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