One of Europe’s most esteemed music institutions, the Sibelius Academy in Finland, has acquired an extremely rare instrument: a radically redesigned quarter-tone piano. With a mechanism almost identical to its regularly tuned cousin, the most conspicuous difference from a conventional piano is the keyboard: instead of dividing the octave into 12 pitches, it is divided into 24. Other quarter-tone piano designs have previously been built but have often been bulky and difficult to play.

Two former students of the Sibelius Academy, pianist Elisa Järvi and composer Sampo Haapamäki, have been collaborating for almost a decade to realise a more ergonomically designed full-size quarter-tone piano. Previous solutions to the quarter-tone piano involved two separate instruments, or multiple manuals, which created limitations on the complexity and virtuosity that could be reasonably expected by a composer. With assistance from the Sibelius Academy development centre, Järvi and Haapamäki first created a one-octave proof-of-concept, before a full-scale prototype of their design began construction in 2014.

The use of quarter-tones is fairly common among contemporary compositions, but the concept of breaking the scale down into smaller divisions is hundreds of years old. The equal division of the octave, known as well-tempered, only became commonplace from the late 17th century. Bach’s Well-Tempered Clavier was the first collection of keyboard pieces to explore the full range of the 24 keys possible with equal temperament. The opposing tonality before this was meantone temperament, which contained microtonal deviations depending on which octave a particular pitch occurred.

Quarter-tonality is also a form of equal, or as it’s sometimes known, circular temperament and composers have experimented with it for decades. One of the earliest pioneers (although by no means the first composer to use quarter-tones) was Czech composer Alois Hába. Among his quarter-tone pieces are a number of piano works, including a Sonata for quarter-tone piano (1946-47), written for an earlier quarter-tone piano design using three separate manuals.