Active control of mid-frequency noise in a vibroacoustic cavity using an inertial piezoelectric actuator

Application of conventional active noise control (ANC) to the mid-frequency band (>200 Hz) in vibroacoustic cavities has been technically restricted owing to the complex acoustic field generated by the use of multiple output speakers. However, as noise control in such frequency bands is essential for modern electric vehicles, this study proposes and demonstrates a novel method for ANC in a vibroacoustic cavity using an inertial vibration actuator. To this end, a prototype actuator is designed using a finite element analysis, and it exhibits a dynamic force of ∼11.3 mN/V_p-p in the usable frequency band (450–750 Hz). An ANC controller for the prototype actuator was implemented on a real-time digital signal processor using a filtered-x least mean squares (FxLMS) algorithm. The ANC system performance is evaluated in a 700 mm × 650 mm × 450 mm rectangular vibroacoustic cavity with a vibrating surface on one side. The proposed ANC system successfully suppresses multiple harmonics associated with the acoustic cavity modes by up to 12 dB at predominant peaks. Moreover, the system operates stably under a wideband (300 Hz) frequency sweep using a single inertial actuator optimally positioned on the structure. The study results indicate that the proposed ANC method shows considerable promise as a replacement for conventional speaker-assisted methods for ANC in vibroacoustic cavities.