The active casing approach is a method to reduce noise generated by a device enclosed in a casing. If the casing provided with the device is thin-walled, control inputs can be applied directly to it, and the whole structure can be used as an active noise barrier. It results in a global noise reduction instead of local zones of quiet when appropriately implemented. However, many devices and machinery do not posses such ready-made casings. Then, the device can be enclosed in an additional casing designed specially for the active control purpose. In this paper such scenario is experimentally investigated, where a compressor is surrounded by an additional light-weight active casing and the real noise generated by the working device is actively reduced. A feedforward adaptive control strategy is used. Filtered-x Least Mean Square (FxLMS) based algorithm in a multichannel structure is used to update control filter parameters. Advantages and limits of the proposed approach are pointed out and discussed.
