A process for quantifying the moisture in a blanket of fibers includes the emission of an incident electromagnetic wave towards the blanket, by at least one emitter; the receiving of the electromagnetic wave transmitted through the blanket, by at least one receiver; the identification of a variation of at least one parameter of the transmitted wave relative to the incident wave; the determination of a representative value of moisture in the blanket of fibers, as a function of the variation and of the effective volume of blanket that has actually interacted with the incident wave.