The Keyboard Dilemma

        Born and raised within the strong folk tradition of Telemark, Norway, Groven's first instruments were the indigenous hardingfele (harding fiddle) and seljefløyte (willow flute), both of which utilize non-tempered tuning systems. It was his belief that Norwegian folk music was based upon intervals of the harmonic series, a hypothesis he presents in his Naturskalaen (The Scale of Nature, 1927). His first encounter with the piano did not take place until he was already a young adult. The Western classical music which he heard sounded so different from the folk music with which he grew up, he found it rather harsh to his ear and considered 12-tone equal temperament to be out-of-tune. Worst of all were the classical arrangements of Norwegian folk music. Groven describes being completely dumbfounded and horrified upon first hearing Edvard Grieg's Slåttar, Op.72, which he considered a gross parody of the actual folk melodies. It was as a result of this clash of cultures that Groven resolved to construct a keyboard capable of playing in pure tuning, or just intonation, first experimenting with the piano, and later switching to organ.

       In the past, the problem with just intonation for keyboard instruments has been that any fixed 12-note tuning was limited to essentially one key. In other words, in order to make the chords used in one key acoustically pure, many of the chords used in other keys would be unacceptably out-of-tune. Historically, there have been essentially two approaches to resolve this dilemma. The most common approach was to modify (or temper) the tuning system so that more chords would be acceptably in-tune. This has resulted in various unequal temperaments, as well as today's standard, 12-tone equal temperament, a compromise in which all chords (and keys) are acceptably in-tune, although none are acoustically pure. A second approach to the problem was to increase the number of keys per octave. These mechanical solutions, such as Giovanni Battista Doni's three-manual cembalo from 1635 with 68 keys per octave, or Julian Carrillo's 1/16-tone piano from the 20th-century with 96 keys per octave, required not only the construction of new keyboard instruments, but performers willing to learn a new, and sometimes awkward, playing technique, and thus never gained wide-spread popularity.

        Groven sought out a solution which would only require a standard keyboard (and keyboardist), yet utilize a larger number of pitches per octave. He took his first inspiration from the phone company, using telephone switchboard relays which, in essence, routed calls from the organ manual to the bank of pipes. 

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At any given time, each individual key on the manual is connected to one of three possible pipes, each tuned to a slightly different frequency. The renstemningsautomat , or automatic pure-tuning device, determines which particular pitch variants are required to produce pure-tuned intervals, and connects the appropriate pipes during the split-second in between when the key is pressed on the manual and the sound is made. The remarkable aspect of Groven's system is that all of this takes place automatically, without the need for any special actions or accommodations on behalf the performer.