“…On the other hand, instruments are constrained in how reliably they can be re-tuned to the same scale. There is a long history [152,182] behind the practice of tuning using harmonic intervals [50,52,59,67,88], and reports exist of tuning according to the step sizes [38,49,51], tuning instruments visually [87,88,96,183], and copying a reference instrument [46,87].…”