Bob and list, I have been one of the lurkers on the list for some time. Your question about the frequency shift of the partials due to different hammer conditions really interests me. From my experience in shock and vibration in the disk drive industry, I would suggest that the condition of the hammer should only change the amplitude of the partials, not the frequency. An example of this in my line of work would be Modal Analysis. When trying to understand a vibrating mode shape of a structure, time domain data can be gathered to "animate" how the structure vibrates at a particular frequency. If the frequency of interest is low, a soft tipped hammer is used to excite the structure. When there is interest in a high frequency resonance, a hard tipped hammer is used. I would propose that the same principle would apply here. Only the amplitude of the partials should change with no change to the inharmonicity. Although a hammer is very nonlinear in compression, is only contacts the structure (string...) to excite it. The response of the string is what generates the sound, and the hammer hardness will only dictate whether the higher partials have much energy content. Care would have to be taken in a real experiment to not change the coupling of the string to the soundboard or aggraffe since the structure would have changed. Just my thoughts... doug richards drichard@qntm.com Quantum Corp. Mechanical Engineer Lurking wanna be piano technician ______________________________ Reply Separator _________________________________ Subject: Voicing and Inharmonicity Author: Robert Scott <rscott@wwnet.com> at SMTP Date: 3/9/97 11:45 AM There seems to be myth that holds that inharmonicity is affected by voicing. I would like to resolve this issue one way or the other. Can anyone report on an actual measurement of inharmonicity that they made that shows a difference in the number of cents of inharmoncity depending on how the string is struck? My own experiments show no difference between striking the string with a felt hammer or using a light tap from a wooden paint stirring stick. In both cases the pitch of the fundamental and all the partials remained the same. Now I realize that the strength of the various partials depends a lot on how and where the string is struck. But if a partial is measureable, it always shows up at exactly the same frequency, at least in my experience. What do the rest of you say? -Bob Scott Ann Arbor, Michigan
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