[CAUT] Semantics

[Escapement]

I'm new to the piano tuning world but I do have a background in computer
science and have worked with signal processing.  I just read through these
posts and have to admit I was thrown for a bit of a loop when I read that
it's now agreed that the soundboard should be called a "transducer." 
 
My understanding of a transducer has always been that it is a device that
takes one form of information or energy and converts it into another form.
(Like the speaker example given where *electrical current* is converted to
physical vibrations through the electromagnetic voice coil).  The speaker
isn't a transducer because the voice coil vibrates the membrane -it's a
transducer because it takes the *electrical current* in the wire and
converts it to vibrations *(sound)*.  In the same way that a microphone is a
transducer because it takes *sound* and converts it to an *electrical
signal*.

But with the soundboard I don't see this conversion.  My understanding of
how a piano works is that the vibrations in the strings are coupled with the
vibrations in the bridge/ soundboard.  But it's vibrations to
vibrations-sound (though very slight) to sound (much louder).  I suppose you
could call the piano itself a transducer in that it (along with the player)
takes the information on the music page and converts it to sound.  But
calling the soundboard a transducer seems odd to me.

I agree that technically, the soundboard doesn't amplify the string energy,
per se, but it does make the sound louder because it is far more efficient
at taking that little bit of energy and converting it into sound energy.

My understanding of the soundboard is that it is a *resonator*-that it
reinforces and emphasizes the sounds generated by the strings, that the
strings and the soundboard work together to make the sound.  It is this
*resonance* that increases the sound output of the piano. 
 
But I don't see the big deal in saying the soundboard amplifies the sound.
Though it doesn't amplify the energy, acting as a *resonator* it does take
that energy and (a great deal more efficiently) converts it to a much
*louder* sound.  And we measure loudness by *amplitude* of the sound/sine
wave.  So, saying the sound is "amplified" by the soundboard seems
reasonable to me.

I mean, are we supposed to say that the soundboard "transduces" the sound to
higher amplitude?  Is that really more instructive than, "the soundboard
helps to amplify the sound?"  To me, it just sounds confusing.  Again, my
understanding is that the soundboard acts as a resonator and reinforces the
sounds made by the strings to increase the sound output. to make it louder.
to amplify the sound. 
 
I don't see a transducer in the soundboard.

When you strike a tuning fork and place it against a table, don't you say
the table amplifies the tuning fork?  Would anyone really argue with this?
Would you really say the table becomes a transducer?  Would it be more
correct to say that the table resonates along with the fork and increases
the sound output?  The table isn't a transducer. the fork vibrates, the
table vibrates (resonates).  And part of the definition of a resonator is
that it "amplifies" vibrations (but again, in the sense described above).

With respect, 

Gary Hodge

PTG - ASSOCIATE MEMBER

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Fred
Sturm
Sent: Saturday, May 09, 2009 10:22 PM
To: caut at ptg.org
Subject: Re: [CAUT] Semantics

On May 9, 2009, at 3:46 PM, David Love wrote:

> However, why can't one say "the volume of sound produced
> formerly limited by the inconsequential mass of the vibrating string  
> alone
> is increased when the energy is transduced to the soundboard whose  
> greater
> mass and area allow for the greater movement of air".  Substitute the
> colloquial meaning of amplified for increased and I don't think the  
> physical
> world as we have come to know it will cease to exist or all soundboard
> science will be endangered.

	Yes, a "larger volume of sound" is produced by a vibrating string  
coupled to a soundboard than is produced by a string vibrating but not  
coupled to a soundboard. But I would ask you to read Del's posts  
carefully. It doesn't really matter that an uncoupled string makes  
sound. The driver of a speaker's membrane makes negligible sound. The  
sound is produced by the vibration of the speaker membrane. The  
speaker membrane isn't increasing the sound of the driver. It is  
producing sound in response to the driver's vibration (the driver's  
vibration causes the membrane to vibrate, which moves air molecules).  
This is very much analogous to what happens with a string and a  
soundboard assembly.
	This doesn't mean that someone who thinks that a soundboard makes a

string sound louder is stupid. It does mean that someone who holds  
that opinion is ill-informed. It is a natural and even logical kind of  
misinformation, which is why it is so widely held. It doesn't help  
that advertising folks for piano manufacturers have been spreading the  
misinformation.
	In any case, it is important to understand the mechanics. And this  
ties back to the original topic, which had to do with the theory that  
string vibrations could be coupled, through accujust hitchpins, to the  
plate, and could make the plate vibrate/resonate in some way. If we  
want to try to see if the analogy between a stake driven into the  
earth, abraded by a hoe, and a string terminated on a vertical pin,  
driven into a hole in a mass of cast iron, has any validity, well, it  
helps to have some knowledge of the mechanics/physics involved, and to  
use words carefully in describing what happens.
	All the hurt feelings and notions of disrespect and anger are very  
much beside the point, and waste a lot of our collective time and  
energy. Let's lose those arguments, okay?
	
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu