Hi Bob: You mentioned that no one has given you data on measurements of inharmon- icity changes due to voicing. Here is some. In your last post regarding voicing having no effect on inharmonicity, I decided to do some tests. First I'll describe some of the setup which I used. Knowing that frequency is affected by amplitude, I devised a key striking system to give rather even strokes to the key. This is a 6" long dampp chaser tube with about 1 1/2" buckshot fill in bottom half covered with a disk made from a ground down dime. On top of that was a cushion of balance rail punchings about 1 1/2" tall, covered with another dime. The remaining cylinder was filled with buck- shot and capped with the endcap of a dampp-chaser rod. The caps were secured on both ends with duct tape. All of this was devised to help eliminate the weight from bouncing when dropped from a prescribed height. A peice of piano wire 8" long was hooked thru the top cap for the purpose of lifting and dropping the weight on a selected key. For a poor man's guidance system, the core of a paper towel roll was relieved on the bottom end to depress the keys on either side of the one being tested. It was found that a 1" striking height would be adequate for most key strokes. With the prepared weight inside the core tube a matrix of piano wires was placed across and thru the tube to limit the height the weight could be raised while being lifted by the 8" long piano wire hook. This first test is limited to note F3 on my Steinway L. Other tests may be done later to see what effects can be noticed in other areas of the piano. In order to avoid damaging the hammer, a strip of thin nameboard felt was passed down between the strings of G#3 and A3 and then brought up between the strings of D3 and D#3. This strip could easily be slid back under the strike point of the F3 when testing for the modified voicing of F3. I realize that this only represents surface voicing effects. More dramatic effects may be realized by deep needling, but as I said, I did not want to damage my hammers. The measurements were taken using the RCT tuning unit utilizing the listening ear which listens to a tone for a prescribed amount of time and averages the readout for that time. This test was not done in an anechoic chamber so there is some variation in readings. Ten readings were taken in each test and then averaged for comparison. The first column shows readings for the unmodulated tone. The second col. shows the tone with the felt placed between the hammer and string at the strike point. F3 partial 4 3.83 3.80 3.90 4.08 3.76 3.98 3.83 3.90 3.92 3.91 3.92 3.77 3.88 3.86 3.73 3.83 3.86 3.79 3.86 3.77 ===== ===== Average 3.849 3.864 F3 partial 3 4.83 5.07 4.92 4.76 5.10 5.02 4.84 4.88 4.85 4.96 4.79 5.03 4.98 5.29 4.97 4.79 4.73 4.95 5.01 5.13 ===== ===== Average 4.902 4.988 F3 partial 2 1.32 1.35 1.33 1.18 1.19 1.31 1.46 1.35 1.81 1.37 1.59 1.22 2.50 1.57 1.22 1.29 1.41 1.32 1.31 1.39 ===== ===== Average 1.514 1.335 The following test was done on F3 listening to the 8th partial. It was necessary to use a much harder blow to excite the 8th partial. I was forced to use heavy finger blows which blows away some possible objectivity but the results were still quite reasonable. F3 partial 8 11.12 11.05 11.23 11.25 11.23 11.11 11.14 11.18 11.12 11.17 11.15 11.06 11.07 11.16 11.13 11.19 11.21 11.20 11.11 11.20 ====== ====== Average 11.151 11.157 As you can see from the above, the voicing change initiated by placing a felt strip between the strings and the hammer does not cause much change in the higher partials, but does produce some change in the lower partials. This BTW goes along with other observed variations in the lower partials which are caused by what we think are variations in soundboard impedance, bridge impedance and perhaps soundboard clamping (too near the edge of the board) and perhaps other unknown to me causes which alter the reading of lower partials more than higher partials. I first discovered these types of variations as far back as 1967. Dean Reyburn has termed this effect as para-inharmonicity. I did some additional testing using the SAT only. F3 partial 4 w/felt 1.4 1.3 1.5 1.3 1.5 1.3 1.5 1.3 1.5 1.3 1.5 1.3 1.5 1.3 1.4 1.4 1.4 1.4 1.5 1.3 ==== ==== 1.48 1.32 After a change in tuning the following measurements were taken. F3 partial 4 w/felt 3.7 3.7 3.8 3.6 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.8 3.7 ===== ===== Average 3.72 3.69 F3 partial 3 prompt end w/felt 0-2sec. 2-6sec. 0-4sec 4-7sec 4.9 4.0 5.0 4.2 In this test, it became obvious 4.8 3.8 4.9 4.2 that there was a good bit of 4.8 3.8 4.9 4.2 difference between the prompt 4.8 3.8 4.9 4.2 pitch and the end pitch, so two 4.8 3.8 4.9 4.2 readings were taken in each case. 4.8 3.8 4.9 4.2 This was not noticed in the higher 4.8 3.8 4.9 4.2 partials. 4.8 3.8 4.9 4.2 4.8 3.8 4.9 4.2 4.8 3.8 4.9 4.2 ===== ===== ===== ===== 4.81 3.82 4.91 4.2 The Averages of each test. 4.315 4.56 The average of the averages. F3 partial 2 w/felt 0-3sec. 3-6sec no change 2.2 1.6 1.6 In this test there was less difference 2.2 1.6 1.6 between the prompt sound and the end 2.2 1.6 1.6 sound during the normal voicing. When 2.2 1.6 1.6 felt was inserted between the hammer 2.2 1.6 1.6 and the string, the softer sound was 2.2 1.6 1.6 the same as the end sound of the full 2.2 1.6 1.6 tone. 2.2 1.6 1.6 2.2 1.6 1.6 2.2 1.6 1.6 ===== ===== ===== 2.2 1.6 1.6 The average of each test 1.9 1.6 The average of the averages Something new was learned in the above tests. Voicing does influence inharmonicity, but mainly inasmuch as the amplitude of the partial is concerned and the part of the tone which is listened to. Up to now I have not considered the latter part of tones, but made estimates as to what the highest pitch at the start of the tone was and made that my reading. This explains why I always felt that voicing affected the pitch or inharmonicity. Well it does, but mostly as a function of amplitude of the particular partial. Jim Coleman, Sr. PS It was hoped that the listening ear with its 2 decimal readings and averaging capability would give us more definitive readings, however, it was discovered that the SAT readings were more dependable. The RCT readings taken by the spinner of the CyberEar were comparable to the SAT, but were slower to arrive at, hence the use of the SAT in the later tests. JWC
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