A composer's imagination reaches beyond realistic physical laws, and aims at illusory, groundbreaking sound creations and sensations. An illusory sound process (trompe l'oreille effect, literally, ear-deceiving) can be created by breaking apart the unambiguous organisation of a musical parameter (pitch, duration, timbre, dynamic, etc.) or the unambiguous coherence between different musical parameters, and, consequently, rendering it diffuse, asynchronous, ambiguous, indistinct. This way, e.g., a multidimensional time organisation, realised through the simultaneous superimposition of diverse textural layers, all with their own (autonomous) tempos and rhythmic characteristics, can generate an estranging sound experience, since a regular, distinct, unambiguous time reference dissolves (during the act of listening). The CREA research project Trompe l'oreille, investigating and creating innovative strategies towards illusive sound-process composition, aims at better understanding these fascinatingly ear-deceiving -and ultimately creative- sound experiences.