Re: [Phys-l] high frequency sounds

["Marc \"Zeke\" Kossover" <zeke_kossover@yahoo.com>]

Copy the file to your computer as a .wav file which is the native format on the CD. As others have mentioned, do not make the file into a .mp3, as that has a variety of lossy compression algorithms which tend to ditch the high frequency parts of the sound since they require lots of data and yet aren't as important to the enjoyment of the song. 


Then you can analyze the sound with the free program Audacity which will allow you to examine the waveform. You can have Audacity play the file at half speed, turning 18 kHz into 9 kHz. You can get a feel for this situation by playing the file at different speeds to ensure that what you are hearing is not an artifact of the program.

Surprisingly, most computer microphones will record well into the ultrasonics and many headphone ports will output in the utlrasonics as well. If yours will do that, you can also use this rather large download <http://zeitnitz.de/Christian/Scope/Scope_en.html> to measure the spectrum of the sound. This program is the only freeware FFT program that I've found that is reliable. 

Good luck,

Zeke Kossover


----- Original Message ----
> From: Anthony Lapinski <Anthony_Lapinski@pds.org>
> To: phys-l@carnot.physics.buffalo.edu
> Sent: Friday, April 17, 2009 4:51:00 AM
> Subject: [Phys-l] high frequency sounds
>
> 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?
>
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