A resonator (1, 1′, 1″) for reducing airborne noise has at least one first ring-shaped chamber (2, 2′, 2″) arranged between an inlet piece (6, 6′) and an outlet piece (7, 7′). An inner tube (3) or inner tube pieces (4, 4″, 5) are arranged between the inlet piece (6, 6′) and outlet piece (7, 7′) and have wall apertures (18, 19, 28, 28″, 29, 29″, 30, 30″) as a connection to the adjacent ring-shaped chamber (2, 2′, 2″). The first ring-shaped chamber (2, 2′, 2″) is divided by at least one radially encircling dividing rib (13, 13′, 13″) into at least two sub-chambers (14, 14′, 14″, 15, 15′, 15″). The dividing rib (13, 13′, 13″) has a free end that, relative to the wall that is adjacent in a radial direction, forms an encircling annular space (16) for receiving an air layer that co-resonates in steady-state.