Neutral layouts arrange musical notes so that there is always the same musical interval between between keys or buttons that have the same spacial relation between them at any place on the keyboard.
The best known neutral systems are the international chromatic button accordion, the Wicki or Wicki-Hayden layout used on some concertinas, and the Janko system intended for use on piano type instruments.
As the interval between buttons which have the same spacial relation is always the same, exactly the same execution ie fingering and keystroke sequencies can be used in different musical keys because the same movement of the fingers at any place on the keyboard always produces the same musical result.
Musical keys can often be grouped, allowing the same fingering and keystroke sequencies for each group of musical keys in a reduced area of the keyboard.
One important advantage of this kind of layout is the drastic reduction of memorisation of scales, chords, arpeggios etc. Consequently, the musician can dedicate less time to overcoming the idiosyncracies of the instrument, and more time to playing music. As a result, learning not only how to play the instrument, but also music in general, is greatly accelerated.
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