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Re: Ultra sound (was MS...)

Subject: Re: Ultra sound (was MS...)
From: "picnet2" picnet2
Date: Mon Oct 13, 2008 10:47 pm ((PDT))
Hi,
    With baudline (www.baudline.com) you can decimate and select the area o=
f interest, re:
Message: 48Khz.
Subject: 

Heres the noise a desk fan makes when bombarded with ultrasound and decimat=
ed down
to our hearing range. (warning loud high pitched noises in the recording)

http://urlme.net/bl/rec/mystery1.wav
The doppler from the individual blade angles can be heard.

Also the Mics on the Edirol R09HR portable recorder will detect upto 48Khz =
if sampling at
96Khz,
http://www.urlme.net/blog/?p=3D71

Failing that Knowles MEM's mic like the SPM0204HE5 for both audio and ultra=
sonic
(complete with a large dose of noise) - or a dedicated part from Knowles fo=
r Ultrasound.

The receiver from a matched pair of 40Khz distance sensors can be pressed i=
nto use if the
FET amplifier from an electret mic (but this isnt the micbuilders group so =
thats off topic :)

-Mike.


> 6) As far as experiencing/playing back high Hz recordings one can a)
> draw spectrographs and try to be happy with them b) slow down the
> playback c) use some sub-sampling scheme to reduce the frequency of
> the samples or d) use some transform or heterodyne technique to focus
> on a specific frequency range and make it audible. What do any of
> these methods (c&d) do to phase information?
>
> I'd be happy to hear what anyone can tell me about any of these topics!
>
> Steve P









"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause


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