# [sdiy] Tap tempo question

Ingo Debus igg.debus at gmail.com
Wed Feb 3 21:36:46 CET 2021

```> Am 02.02.2021 um 22:30 schrieb Mattias Rickardsson <mr at analogue.org>:
>
> Averaging might seem like a good idea to find the tempo, but if you just average a number of periods between consecutive pairs of taps, the end result only depends on the timing of the first and the last tap. The timings of all intermediate taps get thrown away in the calculation since they are first added (as one end of a period) and then subtracted (as the other end of next period).
>
> (If taps occur at times A, B, C, D, E
> then the measured periods are B-A, C-B, D-C, E-D.
> The average of these periods are (B-A + C-B + D-C + E-D) / 4
> which equals (E-A) / 4
> meaning the total time between the first and last taps, divided by the number of periods tapped in between.)

Hehehe…
At least you have to know how many taps occurred between the first and the last tap. Or how else can you know that you have to divide by 4?

Anyway, all this only makes sense if the tempo is constant throughout the whole piece. I believe the idea of tap tempo (opposed to adjusting the tempo with a knob) is, that it’s easier to follow „human“ (i. e. varying) tempo.

Ingo

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