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	<title>Didier Stevens &#187; technology</title>
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		<title>Didier Stevens &#187; technology</title>
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		<title>A Ring Tone That I Cannot Hear</title>
		<link>http://blog.didierstevens.com/2006/06/13/a-ring-tone-that-i-cannot-hear/</link>
		<comments>http://blog.didierstevens.com/2006/06/13/a-ring-tone-that-i-cannot-hear/#comments</comments>
		<pubDate>Tue, 13 Jun 2006 17:10:44 +0000</pubDate>
		<dc:creator>Didier Stevens</dc:creator>
				<category><![CDATA[technology]]></category>

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		<description><![CDATA[Teenagers have a new ring tone that adults cannot hear, because the frequency is too high: 17 kHz. Test it with Audacity: File / New Generate / Tone&#8230; Frequency: 17000 Play it. I cannot hear it. But I can hear a 14 kHz tone. The ring tones are appearing on the net: here and here. [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=blog.didierstevens.com&amp;blog=264765&amp;post=5&amp;subd=didierstevens&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
			<content:encoded><![CDATA[<p><a href="http://digg.com/technology/A_Ring_Tone_That_Adults_Cannot_Hear_(with_MP3)" target="_blank">Teenagers have a new ring tone that adults cannot hear</a>, because the frequency is too high: 17 kHz.</p>
<p>Test it with <a href="http://audacity.sourceforge.net/" target="_blank">Audacity</a>:</p>
<p><i>File / New  </i></p>
<p><i>Generate  / Tone&#8230; Frequency: 17000</i></p>
<p>Play it.</p>
<p>I cannot hear it.  But I can hear a 14 kHz tone.</p>
<p>The ring tones are appearing on the net: <a href="http://digg.com/technology/Cell_phone_ringtone_mosquito_buzz_mp3_download" target="_blank">here</a> and <a href="http://digg.com/technology/Teen_Repellent_Ringtone_available_for_free" target="_blank">here</a>.</p>
<p>Analyzing the first one with Audacity  (<i>Analyze / Plot Spectrum</i>) reveals a peak at 15 kHz.</p>
<p>Keep this in mind when testing:</p>
<ol>
<li>your hardware (sound card, speakers, &#8230;) must be able to handle the frequency (20 kHz is a common limit)</li>
<li>when exporting as mp3, select the right sampling frequencies (<a href="http://en.wikipedia.org/wiki/Nyquist-Shannon_sampling_theorem" target="_blank">Nyquist</a>)</li>
</ol>
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