[CAUT] Semantics

[David Ilvedson]

And they are often way below pitch...

David Ilvedson, RPT
Pacifica, CA  94044

----- Original message ----------------------------------------
From: "Barbara Richmond" <piano57 at comcast.net>
To: caut at ptg.org
Received: 5/14/2009 6:09:08 AM
Subject: Re: [CAUT] Semantics




><big grin>Â Â  



>And...I've heard some pianos that sounded like banjos!  



>br 
>----- Original Message ----- 
>From: "Jeff Farris" <Jfarris at mail.utexas.edu> 
>To: "Ed Sutton" <ed440 at mindspring.com>, caut at ptg.org 
>Sent: Thursday, May 14, 2009 7:50:52 AM GMT -06:00 US/Canada Central 
>Subject: Re: [CAUT] Semantics 

>I'm waiting for someone to say something about imagining the "ideal banjo". 

>Respectfully, 
>Jeff 


>Jeff Farris 
>Piano Technician 
>School of Music 
>UT Austin 
>jfarris at mail.utexas.edu 
>512-471-0158 




>On 5/14/09 1:39 AM, "Ed  Sutton" <ed440 at mindspring.com> wrote: 

>> Just think of "transducer" in terms of its simple Latin roots: it "leads 
>> across" power from one system to another system. 
>> 
>> Now, imagine an "ideal banjo," i.e. a membrane with zero impedence, in a 
>> large open space. If you strike the string, all of the energy is immediately 
>> transduced into the air "Pow!" There is no reflection, no period motion. 
>> Eveything is displaced once, and returns to rest as the impulse radiates out 
>> into the atmosphere. There is no "vibration," but there is still 
>> transduction of the energy. 
>> 
>> In the piano and recital hall, there are many impedences which reflect the 
>> motions and form them into standing waves, which we call vibrations, sounds, 
>> overtones and such. It is still transduction. The sound always fades away as 
>> the energy is absorbed by the many resistances in the situation. 
>> 
>> Ed S. 
>> 
>> 
>> ----- Original Message ----- 
>> From: "Greg Soule" <afmamh7 at bellsouth.net> 
>> To: <caut at ptg.org> 
>> Sent: Thursday, May 14, 2009 1:05 AM 
>> Subject: Re: [CAUT] Semantics 
>> 
>> 
>>> Wow, this has been an interesting thread. Â (some of you probably 
>>> abandoned it long ago) 
>>> 
>>> When I wrote, "I think it is incorrect to consider sound and vibration  as 
>>> two different types of energy.  Sound IS vibration." I hoped it  would 
>>> elicit responses (and I think it did) that would finally clarify  to me 
>>> why it is claimed the soundboard is a transducer.  The way the  term 
>>> "sound" was repeatedly defined simply as "what we hear" I found a 
>>> distraction, because it said nothing to differentiate the types of  energy 
>>> found in the string, board, air, etc., which is the key to  understanding 
>>> the whole kaboodle.  It sounded to me more like some  fuzzy philosophical 
>>> tangent on human perception ("If a tree falls in  the forest . . ."). 
>>> 
>>> So, bear with me while I lay this all out, and tell me if I'm on track 
>>> here . . . 
>>> 
>>> The energy of the string or soundboard has the characteristic of 
>>> vibrating from a fixed point, and the vibrating body is under tension; 
>>> these factors cause it to want to return to a point of repose. Â The 
>>> vibration has frequency and amplitude. Â (Finer points of distinction 
>>> could be made between the ways the string and the board vibrate, but  not 
>>> by me.) 
>>> 
>>> Although the vibrational energy imparted to the surrounding air also  has 
>>> frequency and amplitude, air is a very different kind of medium  because 
>>> air molecules are not anchored to anything.  Since the energy  has no 
>>> fixed point of vibration, it disperses in all directions like  ripples in 
>>> a pond.  It is a vibration that leaves its point of origin  and never goes 
>>> back unless acted upon by an outside force.  This is  the critical 
>>> distinction of acoustic energy. Â Sound IS acoustic energy. 
>>> 
>>> Del Fandrich's illustration brings it home . . . a panel of wood that 
>>> vibrates when struck CREATES acoustical energy in the surrounding  air. 
>>> This is a different type of energy than that of the string or  soundboard, 
>>> and this is why it is proper to refer to the soundboard as  a transducer. 
>>> 
>>> Furthermore, even though the term "transducer" in its most common  usage 
>>> is borrowed from electrical engineering, and electrical  engineers might 
>>> scratch their heads in confusion when they hear piano  technicians use it 
>>> about their pianos, it is indeed the best term to  apply to how the energy 
>>> changes between the soundboard and the  surrounding air.  We use it 
>>> knowingly and confidently. 
>>> 
>>> For further reading class, please see: 
>>> http://www.pianobuilders.com/soundboards.html 
>>> http://en.wikipedia.org/wiki/Sound 
>>> http://en.wikipedia.org/wiki/Acoustics 
>>> http://www.sfu.ca/sonic-studio/handbook/Theme_sound_medium.html 
>>> 
>>> Forgive me for being both dense and persistent, thank you for your 
>>> patience and I respect you all very highly, 
>>> Greg Soule 
>>> (and with a final flourish of self-deprecating humor, he returned to  join 
>>> all the other lurkers) 
>>