Re: [Phys-l] high frequency sounds

["M. Horton" <scitch@verizon.net>]

Why not just open the file with Audacity (free download), Cakewalk, Cool 
Edit, or GarageBand and see if there is a wave there?  Simple calculation 
will tell you the frequency of said wave.

M. Horton

----- Original Message ----- 
From: "John Denker" <jsd@av8n.com>
To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
Sent: Friday, April 17, 2009 7:26 AM
Subject: Re: [Phys-l] high frequency sounds


On 04/17/2009 04:51 AM, Anthony Lapinski wrote:
> This may seem a bit odd, but I (supposedly) have some "high frequency"
> sounds on a CD that are meant only for dogs to hear. Of course, I can't
> hear anything when the disc is played! To be sure the disc is not blank,
> is there any way that the sounds could somehow be reduced to "normal"
> listening frequencies? Is there any software that could do this?

Use your computer.

Use a rip program to copy the CD to a file.

Make sure the ripper does not do any compression.  That is,
check to see that the file is in uncompressed PCM format;
otherwise the compressor could be losing high-frequency
content.

Play the file at half speed.  The "sox" program knows how
to do this.

That's all there is to it.

======

BTW there are numerous other ways to solve the problem using
other sox features (filters, power meters, et cetera).

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