Filtered-x and Filtered-u LMS active noise control in ducts

Prolonged noise exposure can cause problems related to hearing health, resulting in an attention deficit and eventually work accidents. This paper evaluates two methods of active noise control (ANC) in ducts: the Filtered-x LMS and a modified Filtered-u LMS algorithm that improves sound path identification by the optimization of the filters parameters. The ANC system is validated with the design and implementation of an experimental setup. A code was developed in MATLAB software language for microphone signal acquisition and speaker control. In general, the proposed control system obtained attenuations that depend on the type of noise evaluated (monotonal, multitonal, or broadband). The attenuation levels reach 23 dB for the monotonal test; however, in the tests for white noise, the system did not present pronounced attenuation.