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I just glued the fretboard to my first guitar (a Classical), and remembered seeing something in the forum about humming near the soundhole, so I tried it.
Well, I started humming as low as I can manage, and increased the pitch of my hum until the guitar started humming back (pretty loud too) It seems to be humming at or near G sharp. Is there any significance to this?

Our pal Ken Hodges is the one who originally posted the thread about humming in guitars.  Maybe he will weigh in here and tell you what he knows.

"In the Soundhole"? Can you play a few bars?

That pitch is about typical, what most guitars with that body size would resonate at. Dreads are lower. It's what Alan Carruth calls the main air, I think. If your face is too close to the cavity while you're humming, it lowers the pitch of the resonant frequency. To get an accurate assessment, you'd need to be away from the hole enough that you're not causing the hole to seem smaller.

For grins, try holding your hand over say, 1/4 of the area of the soundhole and see what happens to the pitch.

Guess what happened to the frequency of Tony Rice's D-28 when the soundhole got opened up!

Alan will probably join in here. He has lots of fun with this stuff.

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now known around here as Pat Foster
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http://www.patfosterguitars.com

Hehe... I knew I wasnt the only one that hummed in their guitars :D :D

I have found that mine all tend to resonate at or around a G also. I get worried when one of mine doesnt respond to the humming as the others do. So far I have only found one that didnt respond as the others did and began exploring why it didnt. I did some trimming of the bracing and finally got a pretty good response out of it. Just for clarity, the guitar did resonate, but I didnt get the amount of volume out of it that I normally got.

By the way, we are humming, mouth closed, and not blowing air into the cavity. When the right tone is presented, the guitar almost feels like it will explode from all of the vibration. At this time you can also feel stiff spots and loose spots on the guitar, front and back.

I still dont know the effectiveness of this process, but sooner or later I'll have enough guitars to go on to be able to put some kind of meaning to this.

Just out of curiosity, what size was the sound hole on this guitar? My guess is that it was smaller than 4" ??

 

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Reguards,

Ken H

I just blow my air hose across the soundhole at around 90psi.

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Eschew obfuscation, espouse elucidation.

The soundhole measures 3 1/4 inches diameter.


Ray

Ahhhh I thought so. That would explain the slightly sharper resonance tone. Now that you know this, you wil be humming in guitars and feeling the response from now on. You will know in advance whether or not the guitar will sound tight or loose when completed.

Welcome to the club!

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Reguards,

Ken H

If the guitar resonates at G sharp, what will the effect be when playing the G sharp note? Will it be Accentuated, or diminished?

Ray

Usually notes around the pitch of the 'main air' resonance will be more powerful, but you might not hear much difference. 'Loudness' and 'power' aren't the same thing: all else equal you have to nearly double the power output before a thing sounds louder.

You often do notice an effect on sustain. If the resonance is right at G#, and it's very strong, the note might not sustain as long as the G or A. The guitar is extracting the energy from the string faster, so it doesn't last as long, but, again, you're just not as sensitive to the difference in power.

mud daubers nest inside?