Ok, you guys know alot more than me regarding these subjects, but this was something i was disscussing with someone at work the other day.

If you put a waveform though a speaker you can hear it. If you also put the save wave at a 180 deg phase shift at the same time you hear nothing right.

Well maybe this is why a ducks quack doesn't echo.

So if this were true, wouldn't this open up a whole load of stealth technology?

Duck quacks do echo, and canceling sound waves has been known for a very long time and I believe there are some practical machines that exploit that.

Actually ducks quacks don't echo because of the high wavelenght and low frequency. No because they as spitting out sophisticated vocalizations.

Actually ducks quacks don't echo because of the high wavelenght and low frequency.The simply don't carry enough energy. Not because they as spitting out sophisticated vocalizations.

Duck's quacks echo just fine.
http://www.straightdope.com/classics/a5_071.html

Sorry dont mean to be a dick, but a ducks quack DOES echo. If the wavelengths are good enough that you can hear the sound, than it can echo.

Rotating a sound wave 180�� will cancel out the original by counterbalancing the vibrations. It is often refered to as white noise.

quote:

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Originally posted by Prometheus:
Rotating a sound wave 180� will cancel out the original by counterbalancing the vibrations. It is often refered to as white noise.

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While the first part is true, you've got your parties muddled up.

Five points if you get the reference.

I didn't say that was the technical term, I just ment that I have heard it refered to as white noise on more than one occasion.