Impedance-based control system and its application in active noise control - Theoretical analysis

Under conditions of two typical active acoustic reduction strategies, acoustic elimination and acoustic absorption, a general representation of radiation impedance for acoustic source was derived according to the criterion of total acoustic power output. The physical mechanism of acoustic reduction was expounded. The variation of the radiation impedance under conditions of both acoustic reduction strategies was analyzed in detail, in which the primary source is point source, and the secondary source is point source and bipolar source, respectively.