<?xml version="1.0" encoding='utf-8'?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml">
<wml>
<card id="card1" title="Echo - Page 1 - Wikipedia">
<p>
<a accesskey="3" href="page.php?w=Echo&amp;p=2">3.Next</a>
</p>
<p>In <a href="page.php?w=audio_signal_processing">audio signal processing</a> and <a href="page.php?w=acoustics">acoustics</a>, an <b>echo</b> is a <a href="page.php?w=reflection_%28physics%29">reflection</a> of sound that arrives at the listener with a delay after the direct sound. The delay is directly proportional to the distance of the reflecting surface from the source and the listener. Typical examples are the echo produced by the bottom of a well, a building, or the walls of enclosed and empty rooms.</p>

<p><big>Etymology</big></p>
<p>The word echo</p><p>
<a accesskey="3" href="page.php?w=Echo&amp;p=2">3.Next</a>
</p>

<do type="prev" label="Search">
        <go href="search.wml"/>
</do>

</card>
</wml>
