...There is now a great computer program available for instrument makers that works, in my opinion, as well as or better than my Hewlet Packer sound analyzer (a $ 3,000 used lab instrument).
... It is available currently (6/2005) in an advanced beta test version by requesting to part of the test for free.
...When it becomes commercially available, this is one product that should be worth its weight in gold, because it works so well and is easy to use as well.
...To get your copy over the internet contact:

http://www.sygyt.com/en/download
... When you get your copy and install it on your computer, I suggest that you make the following setting changes for doing tap tones on instruments:
  • On the top control bar set the screen output to "LIN" box.
  • In the overtone selector box select '1' if this is not preselected.
  • On the far right slider control, set the left scale to -85db.
  • push 'F5' and select the 'Spectrum' setting and then on the bottom of that screen select the graph 'look' that pleases you most.
  • push' F3' and for the main instrument and overtone instruments select which instrument works the best for you. "Church Organ' might be a good choice to begin with.

Now in the 'tools' ,'Options','Sound Analyzer Settings' select the following:
  • Sampling Rate: 44,100
  • Frequency Resolution 1.3 HZ
  • Time Resolution 5/ Second.
  • Displayed Time Range 0.02 second/ screen {important for tap tuning}
  • Blackman Function If you version does not allow these settings, contact the publisher and explain that you need these setting of instrument tap tone tuning analysis.
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...Now using a one direction inexpensive condensing microphone plugged in to your computer sound card port, push the red record button and holding the microphone near the piece of wood you wish to test, tapping down on the wood with the hard eraser end of a (low toned) wooden pencil (or other tapping device that you find gives good results),
...When you do this tap test, be sure to move away from the noisy fan of your computer or that sound will be added to your recordings confusing results.
...Push the square 'stop' box to finish recording.
...Use your mouse to draw the top box on the sound log to the tap location and adjust its position until you get the clearest picture of the sound pattern.
...Move the first overtone slider into position over the peak (usually the lowest frequency major mountain peak on the graph) and note its frequency. To varify the result, use the left mouse button and 'tap' the box of this slider position and a generated tone at that pitch (and instrument color) will sound. by sounding the tone and immediately after tapping your wood object you should be able to tell if it is higher or lower that the generated tone. Now move the slider (tone) higher or lower until the two match.
....This then is the tap tone frequency of the part you are testing.
...Under the file setting you can save this sound file for later reference or ask that the screen image be either saved or printed out.
...All in all, a fine program!
A special thanks to Bodo Maass the programs author for his help in making his Overtone Analyzer available.
...Here is a typical result of a tap tone on a violin plate (back plate), using this software program. I have identified the fundamental tap tone of the plate (352HZ) as shown. This is verified by comparing the tap tone to the program tone generator until a perfect match is heard. Then the overtone slider bars are moved into position and the graph saved for future reference as below:
...Please notice that even though the 'tap tone' is 352HZ, all frequencies between about 300HZ and 4,500HZ are excited by the tap and just as loud as the fundamental. In fact, you might say that the fundamental tap tone is like the bass part in a multi-voice choir, but it is the one we need to listen for, in order to make adjustments to a violin to produce the best overall power and tone.