Deep systemic differences can be observed between the musical traditions of the Near East on the one hand and Occidental music of large diffusion on the other hand. The modernist acculturation by hybridization with the tonal harmonic system is a dominant feature of the Arabic musical production of the last three quarters of the century. The question of the cohesion at the neutral level of acculturated productions arises as much as that of pointing up allochtonous references. This paper proposes applying the notion of semantic isotopy to the musical field of the Near East, as a technique of authentication, by generalizing the similar approach proposed by Jean-Pierre Bartoli to study musical exoticism. Elaborating an "isosemic index of exosemy", this technique develops a typological approach allowing a classification of musical mix and realizing the notion of acculturative musical pertinence.