An apparatus includes a vibration member, a vibration device connected with the vibration member, a supporting member at a rear surface of the vibration member and configured to include an internal space, and a plurality of holes configured at the supporting member. In another aspect, an apparatus includes a vibration member, a vibration device connected with the vibration member, and a housing covering a rear surface of the vibration member and including a plurality of holes, wherein an internal space provided by the vibration member and the housing is connected to an external space of the housing through the plurality of holes.