---------------------- multipart/alternative attachment John Delacour wrote: > At 5:22 PM +0100 1/9/02, Richard Brekne wrote: > >> Well, see the reason I ask is that your "radiate" seems to >> correspond pretty good with Olsons description of sound board >> radiation in which case I see almost the exact same description when >> it come to Benades description about the longitudinal nature of >> transverse like surface waves. In all this you could sort of look at >> these as a huge collection of tiny ... Olson uses the word "pumps" >> pushing away at the air in his description of sound board >> radiation.... btw.. I read your stress waves reply to Phil and this >> also points in this same direction. You said then >> >> "Acoustic radiation is caused by minute pressure >> differences at the surface of a body." >> > Interesting that Olson should have used such a very similar analogy. > You've mentioned him before but given no details. Who exactly are > Olson and Benades or what are the books in question? > > RB: > > Arthur H. Benade "Fundementals of Musical Acoustics" ISBN > 0-486-26484-X, Dover press New York > Harry F. Olson "Music, Physics, and Engineering" ISBN 0-486-21769-8, > Dover press New York > Neville H. Fletcher & Thomas D Rossing "The Physics of Musical > Instruments" ISBN 0-387-98374-0, Springer > W.V. McFerrin "The Piano, Its Acoustics" > > All available at Amazon.com > > McFerrins book is interesting enough, tho contains the least > information of these four and is the oldest of them. Benades book > should be a must for anyone who is really interested in these aspects > of pianos, and is the easiest to comprehend for the layman. Olson is a > bit heavier, a bit more math intensive.... more for the engineer with > a few years of college level math and engineering behind him. Fletcher > and Rossings book like Oslo requires that you can relate a good deal > of math. I havent read a whole lot in that book yet so I will reserve > further comment. > > JD:The analogy of his tiny pumps or my little pulsating fountains is, > of course, an extreme simplification. The final picture will be > vastly more complicated. What I hope we can eventually arrive at is a > good basic understanding of the principles involved and the nature of > the wave forms generated. As I've recently said, I think it would be > helpful in the early stages to consider the system as composed of one > homogeneous isotropic solid body (which would, I guess, actually work > after a fashion) and to avoid discussion of the behaviour of fluid > bodies. > > RB: > > I agree that a good understanding of these principles, and adherence > to a common terminology based on that understanding would be really > helpfull. My insistance on the fluid bodies examples is as much to > build my own understanding of wave mechanics in general as it is > anything else. Actually Benade puts the soundboard in the catagory of > a 2D plate where longitudinal waves and transverse waves both occur. > And it looks to me like he is saying that one cannot exist without the > other and that where one exists the other must occur. > > Personally I find the whole discussion fascinating and there are lots > of little peices of information that pop up out of nowhere.... For > example...some months ago there was a discussion about something > refered to as para-inharmonicity and there has been quite a bit of > speculation as to what it is and isnt, or indeed if it does exist. > Benade describes some aspects of how soundboard and string modes (as > in partials) effect each other when each have modes whose frequencies > nearly coincide. The description could explain to a "T" the whole > concept of para-inharmonicity. > > > > JD:We have a lot of studying to do. > > Yup...but its fun really. JD -- Richard Brekne RPT, N.P.T.F. Bergen, Norway mailto:rbrekne@broadpark.no ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/de/38/6b/fb/attachment.htm ---------------------- multipart/alternative attachment--
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