Larger piano? was Re: Decibel Levels

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Del posted: 
> There is clearly an advantage to having shear size available when building a
> piano, but absolute power output is not one of them.  <snip> 
>  Piano soundboards are not amplifiers and bigger is not better.  
 
Wim  asks:
<<Are you saying that a larger piano (lets say 7') in a church will not 
necessarily produce a larger sound than a smaller piano, (lets say 5')? <<

 Greetings, 
    I would like to us draw some delineations here.  "Absolute power" and 
"larger sound"  are not really specific enough to allow us much discussion.  
Given that the piano's sound is a composite of multiple frequencies, and 
since human hearing is more sensitive to higher frequencies,(within reason), 
we need to break the spectrum down for comparison.  The first question is 
"How are we measuring the output?" 
    If we measure only the frequencies of the fundamentals,  I think it will 
be evident that the bigger piano has more power, at least, in the bottom half 
of its scale.  If we measure only the partials above the third or fourth, the 
picture can change, I think.  
    Consider a high school marching band.  As they pass by on the street , 
the piccolo and trombones may be the loudest thing you hear up close.  
However,  a 1/4 mile away what do you hear?  The bass drum!  So,  power needs 
to be referred to as a function of frequency, no? 
   It seems that the same holds with pianos, and I have anecodotal evidence.  
On an performance stage, there was and old upright brought in for one scene. 
It's hammers were hard as nails, and when the Steinway D in the orchestra pit 
was played at the same time,  you only heard the upright on the stage. The 
musicians couldn't really hear the grand.  However, at the back of the hall,  
the D was plainly heard and the upright was reduced to a tinny tinkle.  
    Comparing the arch-top guitar to the flat-top: up close, the flat-top 
will usually sound louder, but an orchestra will swallow it whole while the 
arch-top can usually punch its way through.  Isn't this a spectrum-specific 
difference between the two? 
   I see this being a problem with voicing, also. We had two D's on the stage 
here.  The brassy  piano makes the artist think there is a lot of power, 
because it is "loud".  However,  the softer voiced other piano seems to fill 
the room all the way to the back of the hall.  It is producing more 
fundamental. Can we say that the brassy piano is louder and the softer piano 
more powerful?  
Thoughts? 
Ed Foote RPT