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>  >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.  (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.  The >>> vibration has frequency and amplitude.  (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.  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) >>
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