A carder has a drum formed as a hollow cylinder having a drum wall, a longitudinal axis, a circumference, an outer surface, a length, and a clothing provided on the outer surface. Working elements are arranged relative to the outer surface of the drum. Stub axles or a continuous axle is formed along the longitudinal axis of the drum and connected to the drum wall by spokes or disks. One or more acceleration sensors that measures structure-borne sound are mounted on one or more of: a side of the drum wall facing the longitudinal axis, the stub axles, the continuous axle, the spoked, or the disks within the length of the drum.