Lesson 4: Walls and Distance
This lesson is locked
The lessons open up once you have listened to the course introduction, Introduction: Daniel Kish on Echolocation. It is about five and a half minutes long, and it explains what echolocation is and where it came from — everything in this lesson builds on it.
About this lesson
The most practical skill in echolocation: knowing how far away a wall is. Nathan stands right at a wall, clicks, and then backs up step by step, clicking as he goes. The echo starts nearly glued to the click and separates as the wall gets farther away. This is a short lesson because the learning is in the listening — play it several times.
Listen for
- Up close: no separate echo, but Nathan’s voice sounds “pressed” — you can hear the wall in his voice itself.
- As he backs up: the wall’s answer is the first click-echo you hear, arriving quicker than any other reflection because it’s the closest object.
- The moment the wall starts to blur into the general sound of the space — that’s the edge of its range.
- How the nearby building becomes easier to hear than the wall once Nathan is far away.
Try it yourself
Find a wall near your home — a garage door, a fence, the side of the house. Stand close enough to touch it. Talk at it, then click at it. Take one step back and click again. Keep stepping back, one step at a time, and notice the echo pulling away from your click. Then walk toward the wall and try to stop one step before it, using only the sound. Have someone with you the first few times if the space is unfamiliar.
Transcript
Lightly edited for readability.
[Recording check.]
Right here is a wall. It’s really close to me, so if I click at it, there isn’t much of an echo — but you can hear my voice bouncing off it, coming back to me. Now I’m going to back up, and keep backing up. See if you can focus on the sound coming from right in front of me. [He clicks while backing away.] That’s the wall you’re hearing — the first click. It comes very quickly after my click because the wall is so close, and it’s right in front of me.
Getting farther. [Clicks.] Hear that? It keeps getting farther. I keep backing up. [Clicks.] Now it’s starting to mix in with other things. That first click you hear is still the wall, because it’s the closest wall-like object nearby. Can you guess which one is the wall? I already said it: it’s the closest one.
And now, at this distance, it’s much harder to hear — the wall is far away, and the building right next to it is easily heard instead. Now you try this with a wall near your house.