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The Veritune ETD Display

When in the fine tuning mode, Verituner displays the presence of a range of partials on the left side of the display, with the detected overtones indicated with a black triangle (iPad version shown here).
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The numerical values displayed next to each triangle indicates the partial (1 being the fundamental), along with the deviation of the frequency from the ideal values due to inharmonicity (and stretch). Since all stretch is applied relative to A4, the display for A4 shows 0.00 deviation for the A4 fundamental. All other notes will show a non-zero value for the fundamental (assuming it is displayed) that reflects the stretch. The differences for the higher overtones indicate the degree of inharmonicity (in cents) added onto the stretch applied to the fundamental.

The table below shows the measured frequencies of the A4 fundamental and overtones (obtained as described) compared to the ideal values assuming no inharmonicity. The difference between the measured and observed values is shown in the third row (in cents). These values are equal (within expected error) to those shown on the Verituner above for A4 on the same piano (a Steinway B).


1
2
3
4
5
6
7
8
Measured
440.0
880.9
1323.9
1769.8
2219.7
2674.6
3135.4
3603.1
Calculated
440
880
1320
1760
2200
2460
3080
3520
Diff (cents)
0.0
1.8
5.1
9.6
15.4
22.5
30.9
40.4

For comparison the Vertituner display for A3 is shown here.
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The negative value (-2.53) for the fundamental reflects the applied stretch (Koval's 5.1 in this case). The increasing sharpness of the overtones causes this deviation to decrease and become positive for the higher overtones. The measured and calculated values are as follows:
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1
2
3
4
5
6
7
8
Measured
219.8
439.8
660
880.7
1101.9
1323.9
1546.7
1770.4
Calculated
220
440
660
880
1100
1320
1540
1760
Diff (cents)
-1.6
-0.8
0.0
1.4
3.0
5.1
7.5
10.2