Acoustic resonator tuning strategies for the narrowband noise control in an enclosure

The tuning of an acoustic resonator, in terms of its Helmholtz frequency and the internal resistance, is investigated for the control of a narrowband noise in an acoustic enclosure. This paper extends our previous work on the resonance control to a more general scenario in which the noise generated may be either close to, far away from, or in-between the resonance frequencies of the enclosure. Based on a theoretical model, energy radiation and dissipation of the resonator and its interaction with the acoustic enclosure are scrutinized. Numerical studies show the possibility of using mistuned resonators to maximize the noise reduction, as well as the tuning level required for different narrow frequency bands of interests. The effects of the internal resistance of the resonators as well as its dominance levels in the energy dissipation process are also demonstrated. Part of the numerical findings are validated through experiments.