2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/10869I discuss the origin of the ``Sakharov oscillations'' (or ``secondary Doppler peaks'') in standard angular power spectra of the Cosmic Microwave Background anisotropies calculated for inflationary models. I contrast this with the production of CMB anisotropies in `active' models and argue that the presence or absence of Sakharov oscillations will reveal fundamental properties of the primordial perturbations.13 pages including 4 figures. To appear in proceedings of the XXXIst Rencontre de Moriond, `Microwave Background Anisotropies'Astrophysicstext