There are many advocates of this practice. They differ on decisions of which notes to include. The fewer notes needed to do the job, the more efficient the tuning . It is said that the basis of music is the human voice. While this statement ignores older phenomena such as bird calls, it is largely true.
Children learn to sing before they learn to play pianos and violins.
Around the world, most song seems to be based on just intonation . Therefore, the first test of versatility is whether a tuning system can reasonably substitute for just intonation , by imitating commonly-used just intervals . The chart below provides a comparison of several regular tuning systems to just intervals . See also a comparison of weighted harmonic errors . Alternatively, each scale can be defined in terms of the whole-tone, which is the distance between the fourth and fifth.