Gary, Your understanding is correct. Replace the piano strings with tuning forks, the forks' spindles anchored to the piano bridge - the same plane as the strings. Let the hammers hit the prongs of the forks and you have your acoustic mechanical vibrational resonator - the amplitudes of the natural frequencies of/from the tuning forks increase (after the vibrations enter the soundboard) - fulfilling the definition of amplification in mechanical systems - the soundboards' mass and other physical properties increases the the amplitude of the natural frequencies coming from the tuning forks - the impulse energy (containing ALL vibrational frequencies - the blows or strikes from the hammers) imparted to the forks are filtered out - by the forks to only the forks natural frequencies. Have patience. Ron > From: escapement at comcast.net > To: caut at ptg.org > Date: Tue, 12 May 2009 16:11:13 -0400 > Subject: Re: [CAUT] Semantics > > Boy, this just keeps getting more and more confusing. I have to disagree > about "amplitude." Yes, it is a measure of the intensity in wave movement, > but also (and in that very context) of sound level. > > Calling a soundboard an amplifier is misleading (I think, simply) because it > doesn't amplify like a modern stereo system amplifies--i.e., it doesn't > increase the energy level. > > But when sound level is increased, when something gets louder, its > corresponding sine/ sound wave increases in "amplitude," (by definition). > Imagine a sound wave: the frequency of the wave determines it's pitch, and > the amplitude (the peaks and valleys) determines it's loudness or intensity. > > Right, the string has little surface area so it moves little air, creates > little sound. The soundboard has a greater surface area, so it moves a > great deal more air. > > The interesting part, to me anyway, is what they do *together* as a coupled > device. The resonance factor. The soundboard resonates with the strings in > such a way as to greatly increase the sound energy. > > I still don't see the transducer in the soundboard--I just don't see enough > distinction in the energy as it passes from the strings to the soundboard/ > bridge. > > I think I see what you're saying, but I guess I just don't quite get it. > > To me, the transducer argument *de-couples* the strings and the > soundboard--(by doing this "transducing," taking one thing and making it > another). That goes against everything I've read about piano acoustics. > > But I certainly know when to let an issue rest, and I definitely don't want > to rile any feathers here. So I will bow out of this discussion, scratching > my head a little, but much the richer for having participated. > > Respectfully, Gary > > > > > -----Original Message----- > From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Don > Mannino > Sent: Tuesday, May 12, 2009 1:12 PM > To: caut at ptg.org > Subject: Re: [CAUT] Semantics > > Greg Soule correctly pointed out again that definitions vary. Here are > some more miscellaneous but related ramblings on this topic. > > The most general definition for 'transducer' I have found is: > > Any of various devices that transmit energy from one system to another, > sometimes one that converts the energy in form, as a speaker that > converts electrical impulses into sound. > Etymology: < L transducere, to lead across < trans-, over + ducere, to > lead > (Websters New World) > > Note the word "sometimes." The most common transducers we deal with are > electrical to mechanical and vice versa, so this is the most common use > of the word. The word is also correctly applied to a soundboard which > is driven by a large amplitude string movement (of very small area) into > a small amplitude soundboard movement (over a large area). The large > area is what causes the air molecules to move, and is why we can hear it > a lot better, even though the soundboard is actually moving in a much > smaller amplitude than the string. > > If this word "amplitude" confuses matters, it is important to think > about a little, because of its relation to what an amplifier actually > is. Amplitude does not refer to volume of sound, but it is related of > course. Amplitude refers to the size of the movement. So in relation to > a sound, if the air moves with large amplitude it will be loud. But a > string that moves with large amplitude is not necessarily creating a > loud sound, unless it connects to something that makes the air move. > > If you watch a string in the middle of the piano and play it fortissimo, > you can see that the amplitude is pretty large. It is easy to see and > even measure the string movement. Now look at the soundboard under a > good light, and hit the same note hard. Can you see the soundboard > movement? If so, you have good eyes and good light - it is very > difficult to see, because it is very small. > > So this is how the energy is being transduced. It is changed from a > large amplitude vibration of a small area (string) into a large area > small amplitude movement of the air over the soundboard. > > To really argue semantics we could discuss whether it would be more > correct to call the "string / bridge / soundboard system" the > transducer. > > Let's not. > > So to the original thought that it's OK to call a soundboard an > amplifier, well, any word can have alternate uses that are not really > correct, but are still used anyway. But it is my preference to say that > the soundboard makes the sound audible. I stick to calling electrical > things with volume controls amplifiers. Even "guitar amps" is a > misnomer, because this refers to an amplifier combined with a speaker. > But that's what people call them, so this is another example of a > technically incorrect term falling into common usage. As long as > someone says "Guitar Amp" or "Keyboard Amp" then I know they are > referring to a system, not just an amplifier. The technically > inaccurate terminology is understandable, because it is in context. > > Related to some of the fine points people have been debating: There is a > correct and widely recognized term for a system which takes a small > _sound_ wave and makes it louder so that people can hear it. It is not > referred to as an amplifier, but is called a "sound reinforcement > system" which incorporates microphones, amplifiers, and speakers. So > lets follow this lead, and use the technically correct terminology. > Let's call this device that takes finger movements and turns it into > beautiful music a "Piano Forte" (short form: "Piano") It incorporates a > variety of components which combine together, hopefully, to the creation > of beauty in our lives. > > Don Mannino > _________________________________________________________________ Show them the way! 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