Sorry about the link I origionally posted. That was to the abstract. The following link will take you to the downloadable articles he has available on line. You want "Sound Production by a Vibrating Piano Soundboard" The article is in Ghost Script so you will have to get ahold of a reader for that. A quick net seach will yeild you that. If cant get that to work I will see if I can get my very simple ghost script reader to export the file to usual text file format and send it to you. I think you in particular will find some interesting reading here as it seems evident he doesnt quite buy the transverse model. RicB http://www.physics.purdue.edu/piano/articles.shtml On 30.05.2002 at 01:12 Robin Hufford wrote: >Richard, > I have not been able to access the entire article with the link you >included in your post which I would very much like to do. Is this the >correct link? It proceeds only to the abstract which you quote. > I still urge the view that the principal transfer of energy is not, >as he suggests, transverse and would suggest that this is, again an >assumption which has then, mistakenly, been found to be verified by the >discovery of such transverse motion at the bridge, a motion, however, >which has been induced by stress transduction and subsequent wave >development as has been previously described. The two appear, to my mind >at least, to have been confused by the few experimenters that I am aware >of, who have actually addressed the question of soundboard behavior in >pianos. > Quoting from this site: > "The bridge of a piano is the place where two important components, >the strings and the soundboard, meet and interact. The motion of the >bridge is important for understanding soundboard vibrations and sound >production. This motion is also central to the interaction between >strings, and >to coupling of the different modes of a single string.......While the >dominant motion is, as one would expect, perpendicular to the plane of the >soundboard, the experiments show that motion parallel to this plane is >also quite significant. Quantitative results for the in-plane motion are >presented, and its role in sound production is discussed. We also consider >the implications for modeling of soundboard and string motion." > Judging from that which is available at this site no distinction is >drawn between motion of the bridge whether in-plane or otherwise induced >by a lifting up and pushing down of the board as suggested occurs by those >who advocate such, and that of motion induced by superpositional >effects of elastic stress fields, that is wave development in the board >which then carries the bridge. > This is a critical distinction which, of necessity must be drawn for >an accurate answer to this question, so long a source of contention here, >to be found, and is a beginning to a clearer understanding of soundboard >behavior. The few researchers I am aware of who attempt this >question, for example, Wogram, Suzuki and others, appear to approach >soundboard behavior with an assumption that the cyclic loading of the >pressurists is, indeed, the primary method of energy transfer, it being, >apparently, so readily obvious as not to require real investigation, and >move >on, as I have said before, to soundboard behavior. > Perhaps, this investigator will be shown by material in the full >article to have taken this into account, as I sincerely hope he has, >thereby having demonstrated that he, unlike others, has actually >understood the subtleties of this question and been able to answer it >without having >been seduced and distracted by the more readily apparent questions >inherent in the larger aspects of soundboard behavior. The full article >may show this or it may demonstrate that, once again, another researcher >has proceeded directly to these larger questions by way of assumption about >this first, subtle issue. > >Regards, Robin Hufford > >Richard Brekne wrote: > >> Been doing some more reading on this and have the following offering to >submit. Goes to the question of transverse / longitudinal string >vibrational input to the soundboard / bridge assembly. >> >> >From a 20 page article... "Sound Production by a Vibrating Piano >Soundboard" (N. Giordano) >> >> Giordano is the professor of physics and assistant dean of science at >Purdue. >> >> "IV. SOUND PRODUCTION BY AN IN-PLANE FORCE ON THE BRIDGE >> It is well known that the blow of a piano hammer excites both transverse >and longitudinal >> vibrations of the string [2,7]. The transverse vibration leads to a >force on the bridge which >> is directed perpendicular to the soundboard, and thus to sound, and this >sound generation >> has been the main subject of the present work. Longitudinal string >vibrations will yield >> a force on the bridge which is along the string direction, i.e., >parallel to the plane of the >> soundboard. This force will also drive soundboard vibrations which can >produce sound, >> although one might expect that the amount of sound generated by this >mechanism will >> be small. To the best of our knowledge, generation of sound via this >mechanism has not previously been studied." >> >> The whole article (in GS format) may be found at >> >> http://www.auditory.org/asamtgs/asa97snd/2pMUa/2pMUa4.html >> >> and takes the track that non transverse vibratory movement in sound >production from piano soundboards is more significant then previously >thought. He also stresses that the subject matter has been subjected to >such study in the past only by Susiki and Wogram in rather limited >projects. >> >> Happy reading. >> >> RicB Richard Brekne RPT NPTF Griegakadamiet UiB
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