Abstract: An acoustic absorber (10) comprises a housing or wall (11), defining an interior absorber chamber (12) connected by openings (13) to a duct (20) to reduce the sound in the duct (20). The natural frequency and impedance of the absorber (12) are variable, so that the absorber (12) can be adapted to a sound field in the duct (20) in a manner corresponding to the respective operating conditions. Such adaptation is achieved mechanically, for example, by an elastic membrane (15) for varying the volume of chamber (12), or thermally, for example, by a heating wire (14) or a wire braid (17).

Abstract: In order to provide a safety system for a motor vehicle having a gas generator for producing a gas flow, at least one gas outlet opening formed in the gas generator and at least one restraining arrangement associated with the gas generator, which system may provide better comfort for vehicle occupants during production of the gas while retaining those properties of conventional systems that are relevant from a safety point of view, the safety system includes an arrangement for enhancing comfort which is associated with the gas outlet opening and influence, in particular damp, a frequency profile generated during the emergence of the gas.

Abstract: An acoustic absorber (10) comprises a housing or wall (11), defining an interior absorber chamber (12) connected by openings (13) to a duct (20) to reduce the sound in the duct (20). The natural frequency and impedance of the absorber (12) are variable, so that the absorber (12) can be adapted to a sound field in the duct (20) in a manner corresponding to the respective operating conditions. Such adaptation is achieved mechanically, for example, by an elastic membrane (15) for varying the volume of chamber (12), or thermally, for example, by a heating wire (14) or a wire braid (17).