This dictionary offers a guide to microtonal music and musicians of the 20th and 21st centuries. It includes entries on composers and artists such as Julian Carrillo, Alois Hába, Charles Ives, Mordecai Sandberg and Ivan Wyschnegradsky, Giuseppe Tartini, Christiaan Huygens, the physicist Adriaan Fokker, Franz Richter Herf, Harry Partch, Lou Harrison, Ben Johnson, spectral music composers such as Tristan Murail and Gérard Grisey, Alain Bancquart, Georg Friedrich Haas, and genres such as ambient music, drone music, jazz, and metal and others have continued this quest for a new space of microtonal, inharmonic and non-tempered music. This dictionary provides a comprehensive overview of microtonality since the turn of the 20th century, listing more than 500 composers and gives nearly 600 bibliographical references.

Franck Jedrzejewski (1958–) is a researcher and Professor in mathematical physics at INSTN/CEA (Paris-Saclay University). He has also a PhD in music and musicology and in philosophy. In 2013, he was elected Director of program at College International de Philosophie (CIPh), an institute founded in 1983 by Jacques Derrida, Francois Chatelet, and Dominique Lecourt. He has published more than 30 books, most of them in French, and three books in English: Mathematical Theory of Music, Looking at Numbers with the composer Tom Johnson, and A Compendium of Mathematical Music.