1What a clap actually does
Sound races out, then it hits a wall
You only need two ideas. Watch each one:
A clap races out as sound
A clap is a quick burst of sound that flies out into the room. It keeps going in a straight line until it runs into something.
The wall bounces it… or eats it
A hard wall bounces the sound back — that bounce is called a reflection. A soft wall soaks it up and the sound is gone.
2Two kinds of wall
The keep-it-going wall vs the eat-it-up wall
When the clap reaches a wall, the reflected strength depends on the wall, the sound frequency, and the angle:
The keep-it-going wall
Rock and tile bounce almost all the sound straight back — so it can bounce again and again.
The eat-it-up wall
Pillows, carpet and curtains soak the sound up — most of it vanishes the first time it lands.
3Your turn — change the room
Stretch the room and watch the bounce
These walls are hard rock. Slide the room from a tiny closet up to a giant cave and watch the clap fly out, bounce, and come back. The farther it travels, the longer it takes to return.
4Now the real test
Can one padded wall change the echo?
Keep the room the same size. This time only the left wall gets padding; the right wall stays hard. The model clap travels back and forth between those two walls. What will one soft wall do?
Guess before you clap
Compared with two hard walls, will padding just the left wall shorten this back-and-forth echo, or must both walls be padded before anything changes?