Based on an analysis of the evolution of the barometers used by two author societies, the SACD* and the SCAM**, from 1980 to 2007, this article examines professional and inter-generational conflicts pertaining to barometer settings. It shows that the barometers, initially based on the principle of originality of the work and independence of the author in relation to pre-established standards, are now based on principles related to audience flows and programme schedules. The case of barometers therefore clearly illustrates the tension between a regime of cultural singularity and a regime of economic equivalence characterizing the culture industries. SACD?: Soci?t? des Auteurs et Compositeur Dramatiques SCAM?: Soci?t? Civile des Auteurs Multim?dia