Does Guitar Player Shape Affect Tone?

[ST]

Does guitar shape affect tone? + Dunkin' Donuts = Does Guitar Player Shape Affect Tone?

View the following material through a mental lens that the loudspeaker is the guitar body as viewed in profile from the butt end.

Loudspeaker Baffle



Re-Imagined with a Guitar


Loudspeaker without Baffle


Re-Imagined with a Guitar



Question

Does guitar player shape, (or mass, or proximity, or contact area) influence tone?

[cke]

Donuts sure affect MY shape!~ Yes, we are part of the system

[unclrob]

Yep.

[abalone at last]

resting your arm on the soundboard can effect tone so if you have a big old arm on there I'll say yes. 

[broKen]

Yes sir! When I keep the guitar off my belly (I stand when playing), it sounds much more vibrant. The pick and attack make a big difference also.

[hadden]

As mentioned lose the beer gut and keep beefy arm off the top.

[Michael T]

My JP armrest sure helped mine, & keeps the wear down on the finish too :)

[tadol]

A couple of my more responsive guitars definitely sound different when I am sitting forward and the back is not against my body. But I only notice it on a couple. If I am not intentionally muffling the top, I can't hear alot of difference with my arm held away, but I've not tried an arm rest either.

The loudspeaker analogy is good - it shows how the kerfing acts like the speaker baffle allowing the top to resonate while held in the frame of the sides and back. But its a speaker thats driven from the front -

[rockstar_not]

The speaker enclosure is an interesting analogy however, the physics of the situation are not analogous.

The speaker enclosure functions as a resonating chamber for the speaker driver itself, just as the guitar body performs the same function for the vibrating strings.

If you had the winning jockey from the Kentucky Derby hold a speaker, in an enclosure, against his/her midsection and played a song through it, it would sound no different out in front of the speaker than if Andre the Giant held the exact same speaker against his midsection.

The ONLY differences if these two people held and played guitars might be those mentioned by some above - the damping differences that COULD result from arms resting against resonating surfaces; angle differences between arm positions and guitar resulting in picking angle differences, radiation pattern differences due to the angle of the guitar relative to the floor, etc.

But make no mistake, the body of the guitar matters much more than the person's body playing the guitar.  The 'dephasing' diagrams really don't apply too strongly to the situation of an acoustic guitar because of the huge difference in levels of waves radiated from the soundboard of a guitar vs. the back.   Just pluck one string on any of your acoustics and have someone 'twirl' it around on the axis formed by the neck and you'll hear the huge level difference as it spins around.  This means waves radiated from the rear of the guitar have quite little influence on those radiating from the front of the guitar.  With a suspended loudspeaker, as you have shown in your diagram, the situation is much different - nearly equal levels radiated from the front vs. the back of the speaker.  This all deals with the concept of constructive and destructive interference.  Relative magnitudes of the waves doing the interference matters quite a bit.

Finally, as an extreme example of what you are asking about, another simple experiment to convince yourself of this would be to have someone play an open chord on one of your acoustics and immediately suspend it in front of perhaps a piece of plywood; perhaps 2' x 3' to represent a 'small person', sound hole facing out.  Then perform the same thing but suspend in front of a 4' x 4' sheet, same distance away, to represent a 'large' person (really large!).  Then hang a thin blanket over each to represent their clothing.

You'll notice very little difference, particularly with the blanket draped over the plywood in each case. 

[cke]

The speaker enclosure is an interesting analogy however, the physics of the situation are not analogous.

If you had the winning jockey from the Kentucky Derby hold a speaker, in an enclosure, against his/her midsection and played a song through it, it would sound no different out in front of the speaker than if Andre the Giant held the exact same speaker against his midsection.

There is the effect of 'baffling'

[ST]

Hi rockstar_not,

The speaker enclosure is an interesting analogy however, the physics of the situation are not analogous.

The speaker enclosure functions as a resonating chamber for the speaker driver itself, just as the guitar body performs the same function for the vibrating strings.

In the diagrams in the lead post I was suggesting that the guitar body is the loudspeaker (not the enclosure). 

[ST]

Hi cke,

There is the effect of 'baffling'

What is baffling me is that this  started off as a weight reduction initiative:

Originally posted by ST:
Does guitar shape affect tone? + Dunkin' Donuts = Does Guitar Player Shape Affect Tone?

I mean - who can eat a donut with a tongue planted in his/her cheek?


It's been great to see this turn into something more serious. And I really did want to suggest in a light-hearted way that I think time could be better spent behind a guitar than in front of a computer and to suggest that who and what we are, and the way we embrace guitar will have a great deal more to do with tone than the shape of the object we hold so dear.

[rockstar_not]

Hi rockstar_not,
In the diagrams in the lead post I was suggesting that the guitar body is the loudspeaker (not the enclosure). 

Well - that is where there is a huge difference in the analogy and the situation of a guitar player and his/her axe.  In a loudspeaker system, the speaker and the enclosure are highly coupled (in engineering physics terminology).  The guitar player and the guitar are highly de-coupled and the analogy with a guitar body as the speaker, and the player as the 'enclosure' breaks down as a result.

It's an interesting question regardless.

Again, I suggest that the mere angles of how the guitar is held relative to the listening location, as affected by the size/shape of the player, have more to do with what the differences in sound might be than the sound being reflected off of the player.  Also the damping of the back and top would matter relative to the player's size/shape and how they hold the guitar.

You have done some nice pickup comparisons here in the past.  Just try it for yourself with the same mic, and hopefully same playing technique, with mic positioning.  Do it on the front  side of the guitar, then make an attempt to mic the back side and rove it around if you can (assuming there's some room!).  You'll notice much smaller effects on the back side, and lower levels, than roving the mic around in the front.  So much so, that the 'dephasing' or destructive interference of waves coming from the back of the guitar vs. the front, has negligible effects relative to other effects already listed.