Kalevi Aho composed Quasi una fantasia for horn and organ (2011) on the request of organist Jan Lehtola, who premiered it with horn player Petri Komulainen 11th March 2012 in Helsinki, Finland. The piece is extremely virtuosic, and almost concerto-like in nature. At times the horn plays also quarter-tone scales by combining ‘perfect' and ‘imperfect' (the 7th, 11th and 13th) overtones of different harmonic series together.