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What causes echo?
Tuesday, 29 June, 2004
What causes echo on phone calls and similar? Electricity travels at the speed of light. so it can't be anything to do with distance. It's on some phone calls and Internet calls but not others.
Les Astin, Noosa, QLD
 Echo is caused by a couple of factors.
The first IS related to the speed of light. Electric currents in wires and radio waves in space both travel at around the speed of light -- approximately 3x108 metres per second. (300,000 kilometres per second). That means that there is an appreciable delay as your voice travels around the world to the other phone, and then some of it is allowed to come back to you. If the phone call goes via a satellite, then the path is longer, so the delay is longer too. However, modern phone systems normally eliminate the echo so it isn't a problem.
The second source of delay is the fact that the voice is converted to a digital signal, then sent in small packets of data which are recombined at the far end, then turned back into audio. Depending on the system used (and the priority of the data) there will be added delays. That's why a phone call made via a cheap calling card is so bad -- it's made using low cost Internet telephony.
Paul Zucker
 Reader solutions
chiamakaPosted: 29/06/2009 re: What causes echo? echo is caused by a mismatch between the balance network impedance of the hybrid transformer used in telephony and that of the local loop
(Not what we're talking about. -PZ) mariaPosted: 28/03/2008 What is an echo? explain it simple.
(And echo is a sound that's repeated after a short delay. -PZ) haremedPosted: 21/01/2008 re: What causes echo? i think he is voice comink back from long distens away no doubts alishaPosted: 09/11/2007 re: What causes echo? how does an echo work
(That's a big question Alisha. An echo occurs when a sound is heard directly, but also heard again, slightly delayed. It might be a natural echo, such as from a nearby building, or an artificial echo such as on a telephone line. Some echoes have many repeats of the original sound, getting softer each time. You should look it up in an encyclopedia for a full explanation. -PZ) JojoPosted: 29/10/2007 re: What causes echo? Yes, yes. Terri GrantPosted: 17/01/2007 re: What causes echo? i think echoes are caused by sound affects that act upon it. AndyPosted: 06/06/2006 re: What causes echo? Make it simpler so jackasses can understand.
(Sorry Andy. Echo is caused by the fact that the signal takes a while to get from one end to another. If there is also feedback, the sound gets picked up and sent back so the echo repeats. -Paul Zucker) Pranesh PalPosted: 29/06/2004 re: What causes echo? http://www.eskimo.com/~billb/miscon/speed.html |