Talk:Railsback curve

''This page has been merged into Talk:Piano acoustics. Please have future discussions there.''

Edit June 9, 2006
Reasons for my edit on June 9, 2006:


 * 1) Piano technicians are indeed conscious of this effect; understanding of it is essential to the proper tuning of the piano. Though this process has arisen out of a process which is intuitive, this does not mean that a piano tuner doesn't know what's happening.
 * 2) The paragraph beginning If inharmonicity is not taken into account... makes strange suggestions about tuning practice. What I mean is that inharmonicity needs to be taken into account in order to produce a tunning that ignores it. (This is related to the first issue about it being the intuitive approach.)
 * 3) The intensity of sound only really varies between zero and maximum when the two tones are equal in intensity. (I'm removing this little inaccuracy, and leaving the reader to find a more detailed description at the beat article.)
 * 4) Two basic causes: this is incorrect. The lower strings are not substituting the resonance effect; the primary cause is still string stiffness which is augmented by resonance more in the bass. There are more details to the strings of a piano, which I have grouped with a revision of the above under shape of the curve.

Rainwarrior 23:03, 9 June 2006 (UTC)


 * I'm also suggesting we merge this page with Piano acoustics, as the latter contains the same content in less detail, but has a more general title, giving it the possibiliy of containing more at some later point. - Rainwarrior 23:18, 9 June 2006 (UTC)


 * I'm basically happy with the changes. You're right; I shouldn't have suggested that technicians are generally unaware of the effect.  I did wonder if they were sometimes unaware of the named curve itself.


 * I'm not in principle opposed to a merge, but I'm concerned that people wouldn't be able to find the contents via the title "Railsback curve." I wasn't able to find out much about it through either a Wikipedia or a Google search, which is why I wrote the article in the first place.


 * Incidentally, with respect to stiffness-induced inharmonicity, I have a paper here which suggests that it accounts only for about 5 cents worth deviation in the lowest octaves, and that the rest is due primarily to resonances from the soundboard. I'm not sure the reference is kosher--do you recognize it?  L.I. Ortiz-Berenguer, F.J. Casajus-Quiros, M. Torres-Guijarro, J.A. Beracoechea, "Piano Transcription Using Pattern Recognition: Aspects on Parameter Extraction."  In Proceedings of the Seventh International Conference on Digital Audio Effects, pp. 212-16, 2004.  Am I misinterpreting this paper?  I was going to post this citation, but I thought I'd wait to see if this interpretation remained in the article. BrianTung 07:12, 10 June 2006 (UTC)


 * You can redesign bass string core and winding diameters, and unwound parts to change inharmonicity with good predictability without doing anything to the panel, it's a subject that has received a lot of attention since 1938, here's some literature that I found useful: Harvey Fletcher, (1964) "Normal Vibration Frequencies of a Stiff Piano String" JASA V.36, n.1 ; Firth, Ian (1986) "Overwrapped Strings: Design Guide" Journal of the Catgut Acoustical Society N. 45 ; Sanderson, Albert "Piano Scaling Formulas" Piano Technology Topics (handout) ; Roberts, David (1990) The Calculating Technician, Piano Technicians Guild Foundation. I don't remember any one of them mentioning "Railsback curve" and even inharmonicity curve is a little misleading because there usually are discontinuities for instance from string winding variations. Mireut 12:58, 10 June 2006 (UTC)


 * If I did a merge, Railsback curve would still redirect you to the acoustics page, where it would have its own prominent heading. For familiarity with the term, I'd seen many graphs of the curve but I didn't actually remember the Railsback name from it. (In response to Mireut below, yes, "inharmonicity curve" isn't the right term at all as it is discontinuous and shaped differently, though it would be a related curve, a derivative of the Railsback curve.) I haven't heard of this Oritz-Berenguer et. al., though its title intrigues me (music recognition algorithms are right up my line of interest), but the title suggests that this article is about research about computer tone recognition, rather than on piano acoustics itself, meaning that any information on piano acoustics in that article was probably gleaned from other sources. I had a good reference on the subject lying around here at one point, but I have temporarily misplaced it; intuitively I would point out that if the soundboard resonance was the main cause of inharmonicity in the bass, large grand pianos would not have much less inharmonicity than uprights, as they do. - Rainwarrior 15:38, 10 June 2006 (UTC)


 * Actually, the article is (perhaps surprisingly) at least half about the actual acoustics, and if I recall correctly, it gives every impression of adding original content in that area. I don't have it with me at the moment, but when I get back in the office, I'll check it again. BrianTung 21:00, 10 June 2006 (UTC)


 * I found it here. I'll take a look. - Rainwarrior 22:05, 10 June 2006 (UTC)


 * Ah, I think I understand. In the conclusion the article states that "lower partials are very affected by the soundboard and their use must be avoided", which I believe means that the bass frequencies are very hard to use for tone recognition, but then it follows that for notes with fundamentals in this range, higher partials can be used instead (because of how difficult it is to guess soundboard reasonance). So, my interperetation here is that in the lowest frequencies string inharmonicity is overcome by soundboard inharmonicity, but not at all frequencies output by the string. By and large, I think string inharmonicity is still the main factor (which plays out in the grand vs. upright psychoacoustical anecdote I related earlier). - Rainwarrior 22:40, 10 June 2006 (UTC)