In its most general sense, the transfer or morphing of characteristics of one sound to another. It is therefore closely allied to the notion of transformations of sound.
However, the term has a more precise meaning in the work of the composer Karlheinz Stockhausen, who during the 1960’s, in the context of his serialist aesthetics and ’universalist’ spiritual ideology, was much occupied with how to integrate heterogeneous sonic material using strategies other than collage. Employing studio techniques based upon multiple ring modulation, Stockhausen intermodulated, or ’fused’, excerpts of existing musics from diverse cultures (Telemusik -1966) or multiple national anthems from around the globe (Hymnen -1967). This sense of the term therefore reveals a cultural as well as technical dimension.
Bibliography: Souster, Tim (1977). Intermodulation: A Short History