questions about echoes

[ph1sher]

First of all, what properties of a sound make for an optimal echo?

And second, I just saw a show that claims a wolf echo does not make an echo:

http://animalplanet.discoveryeurope.com/50outrageousanimalfact
s/feature8.shtml

I don't believe that at all since it makes no sense, but is there any merit to that claim (which is why I asked the first question)?

[ph1sher]

easier link

http://animalplanet.discoveryeurope.com/50outrageousanimalfacts/feature8.shtml

[aommaster]

well, I also heard that a duck's quack doesn't echo. I don;t know why though. As for normal echos, the property of sound is that it is a longidudinal wave that can bounce back. When you shout in an empty room, the sound bounces off the walls (not all of it, some of it) and you hear it.

Hope that helps

[Sayonara³]

Duck's quacks do echo - the myth that they don't was debunked last year.

Perhaps this "wolves' howls don't echo" is the replacement?

[aommaster]

yeah, i'm still trying to figure out the reason. Why can't it echo, it should. Shouldn't it?

[YT2095]

hetrodyne phase cancelation would be my guess.

[aommaster]

ummm. in simple language please??? lol

[YT2095]

imagine a waveform, /\/\/\/\/\/\/\/ etc...
now think of an inverse or phase inverted waveform so that peeks /\ <--- the top bit exactly match the troughs \/ the bottom bit.
when the 2 are added together you`ll get what`s known as phase cancelation, the RMS when 180 degrees out of phase will be practicaly Zero.

if the echo acoustics are correct, this will occur with a single tone, (think about a wolfs acll, it`s long and almost single frequency and certainly a near pure sinewave) the bounce back echo will apear almost non existant and certain angles will be almost silent (phase canceled). with co-phasing it will act as an amplifier also :)
as for echo, at such sound sample, it would indeed apear negligable :)

[ph1sher]

that's pretty much what i was thinking, something along the lines of pure tones (equal peaks and troughs with no fall off), so no harmonization. But my understanding of waves and acoustics is rudimentary at best so I just wanted to ask.

I was just bothered when I heard the statement, "wolf howls make no echoes" since it was reminiscent of the duck myth which I always had thought was ridiculous. Probably should be, "howl echoes are hard to perceive."

[YT2095]

wolves make an echo just the same as any other sound, be sure :)
it`s just the way it`s perceived as you say :)

[Atlantic]

they all echo. The only way they wouldn't echo is if you stick them in an air column designed perfectly for their sounds, and cause destructive interference. These are just myths, they do echo!!! :)

[Pinch Paxton]

Echoes have something to do with abruptness. I presume that an abrupt sound is tightly compacted. Its like dropping a sugar lump in water. It remains in a block state for awhile, so if it were sound, you would hear it on its return journey. The same amount of granulated sugar would dissolve quicker, this would be the Wolf howl. The wolf howl is a strip of sound, spread outwards, less compacted.

Pincho.