I'll also get Tracy's test engine going on his test stand and make
a few noise measurements with my DB meter with the muffler
that is on his test engine now. Then we will bolt this muffler on
and repeat the measurements. This will give all who attend a chance
to see it and hear it. It will also give us a reference number for an
existing muffler. Something I don't have here right at the
moment let alone a working test engine. We can also compare it to Tracy's
and Chucks engine noise and what ever other rotary powered airplane attends.

I'll check this out with Tracy tomorrow by phone as I am sure he is busier
than an one arm paper hanger.

Paul Lamar

"Steere, John" wrote:

Paul;

If you are interested in a more analytical look at the relative performance
of the two mufflers, and have access to a Compaq iPAQ, there is a very neat
little program available that turns the iPAQ into an audio spectrum
analyzer.  It is called (HASA) Handheld Audio Spectrum Analyzer v2.2.  HASA
takes samples of the sounds picked up by the built-in microphone on the
Pocket PC. It then applies a Fourier Transform to the samples, and obtains
their frequency spectrum. In the bottom third of the HASA display you can
observe the sound samples as they are picked up by the microphone.  The
program allows you to store spectral samples for comparison purposes.

There is a free download with a 100 sample limitation, or you can buy the
full blown program for $15.  No, that is not a typo.

The web site is http://ipaq.pdatopsoft.com/software/item.php?pid=603&

John Steere
BD-4 3.8L Ford SC engine

Thanks for the tip John. I think Tracy has an Ipaq

Paul Lamar
 
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