A braking band for a disk-brake disk which is capable of exceptionally quiet braking comprises at least two plates connected to one another by connecting elements, in which the space between the plates forms an internal air-duct for the cooling of the braking band. At least one of the plates has, in one of its surfaces defining the air-ducts, at least one groove which extends along at least a portion of an orbit around the axis of symmetry of the disk and the cross-section of which becomes wider towards the air-duct.