In the 1970s, as a composer and researcher at Utrecht's Institute of Sonology, The Netherlands, he developed pioneering programs in the field of computer-generated music.

[2] In 1951, blending his interests for mathematics and music, he received his doctorate with a study of the structure of Johann Sebastian Bach's Inventions and Fugues.

[6] From 1963 to 1970, Kaegi worked at the Centre de Recherches Sonores, the electroacoustic music studio of Radio Suisse Romande in Geneva.

There he started composing electronic and tape music, including pieces such as Éclipses (1964), L'Art de la Table (1964), and Entretiens (1965).

[9] In the 12 pages accompanying booklet, Kaegi analyses the basic constituents of electronic music like sine wave, sound synthesis, ring modulation or electronic oscillator, with sound examples provided on the disc as well as excerpts from his most recent works of the time, Kyoto, 1970, Thai Clarinet, 1970, Hydrophonie I, 1969 and Illumination Expo'70 Osaka, 1969.

At the Institute, Kaegi worked as a composer, researcher and teacher in the field of electronically generated music and composition – his students have among others included Benno Ammann, Lasse Thoresen, Jos Janssen, Cort Lippe, Kathleen St John, Trevor Batten, Maarten In 't Veld, Martin Supper, Peter Pabon, Kees van Prooijen.