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Old 03-09-2018, 08:45 AM
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KevWind KevWind is offline
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Quote:
Originally Posted by Picker2 View Post
It is always allowed to reach conclusions by scientific reasoning plus observations of one experiment to predict observations of another experiment - as long as you stick to generally accepted scientific principles.

In this particular case I don't get why AP stated that if you fret the high E at the 12th fret (659 Hz), the fundamental will also resonate (329 Hz). It doesn't, and it never will. That's the whole point of fretting a string. I assume it was just a slip of the pen, or maybe he meant it the other way around: if you hit the open E string (329 Hz) the first harmonic (659 Hz) will sound along with it. This is indeed true.

The recording of the body resonance after tapping the bridge may seem to be an odd thing to do, but it is a well-known method to capture the properties of acoustic systems (room ambiance, echo's, but also stringed instruments). The method is widely applied in digital audio processing, e.g., convolution reverb. It's a standard method in digital signal processing, and there are countless text books describing it.

There is no point in recording the string pluck to test the body resonance. The string pluck will only generate a very limited number of frequencies. It's like taking a picture through a couple of narrow slits. A short tap, however, generates all audible frequencies in one go and feeds them to the top. The top will then resonate with those frequencies it supports. Since the tap contains all audible frequencies, you can be sure you never miss one.

Regardless all of the above, my most important statement is that body resonant frequencies in a guitar are always so short and so unspecific that they will never interfere with the frequencies generated by the strings as they ring out. And this is what the whole "better-in-tune-ness claim" of V-bracing is about.
I understand the scientific use of a tests of one thing to predict results of something else , in very specific instances , But there is no reason to do so in this particular case.

Of course there is a point recording the string pluck to test and verify the body resonance produced by plucking the E string at the 12 fret (the statement you claim is not true) and there is no logical reason not to , in order to prove or disprove AP's specific statement. It does not matter how many body resonant frequencies the string pluck will produce, because those frequencies are the only salient frequencies involved in AP' statement.

I may not have a degree in physics, but I have a Masters Certificate in Advanced Audio Production in Pro Tools and 15 years experience recording digital audio. So I am knowledgeable enough to know there is no logical reason not to use the same recording chain you used to record the bridge thump to record the string pluck . And your assertion that in this instance recording the tap will yield applicable results is flawed reasoning because it introduces unnecessary variables. Like the for example the bridge will not vibrate the same nor as long, as the string. The reality is that if you record the string pluck just like you recorded the tap, the resulting graph will show if there is any increased signal peaks below the E5 note . And might even prove you right .
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