Echo

Donated by Lara Odell

Sound waves are reflected by matter. An echo is one kind of reflected sound. Sound waves bounce off an object and are reflected back to the source. Smooth or hard surfaces (like the grand canyon) reflect sound best. Soft, or rough surfaces tend to absorb sound waves rather than reflect them.

Museum curator Kye Potter argues that an echo is not a double but rather a multiple. He thinks sound waves bounce off of multiple spots (within a cave for example) and that the waves are thus tripled and fippled, etc., bouncing back from different distances, hence the effect: hello… hello… hello… hello… etc. and not just “hello…hello.” Kye suggests designing a long half-sound-proofed room with one smooth wall so that the sound of your voice would travel back only once.

In linguistics, an echo question is a question that:

* occurs in the turn after a repairable utterance, and

* repeats the portion felt by the speaker to need repair.

Here is an example of an echo question:

A: I need a new bolt for my oil filter.

B: A BOLT?

A: I mean for my oil pan.

See also the plays and films of David Mamet.