Re: [Phys-l] high frequency sounds

[Bernard Cleyet <bernardcleyet@redshift.com>]

Ha ha!

I live in an ancient analog world still.  Bat detectors mix a local  
oscillator w/ the bats signal.  The difference one hears.

bc  really retired.

p.s. My LA Phil. violinist friend used a high power Hi Fi amp and  
oscillator to drive an NAB OR tape recorder while playing back  
normally recorded voice at such a greater speed it was unintelligible  
to me; he had leaned to "hear" it.  He was even more hyperactive than I.



On 2009, Apr 17, , at 07:26, John Denker wrote:

> 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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