Research on broadband resonator with extended soft neck for low frequency

A new structure for the broadband sound absorption is proposed in this paper.Based on the sound absorption mechanism of Helmholtz Resonator,the advantage of soft tube length is fully used in the new structure,and thus the low-frequency noise can be controled easily.The acoustic boundary conditions in different areas are set up based on a consideration of the wall characteristics of soft tubes, and then the theoretic sound absorption characteristics of this new structure are given.The proposed mechanism for the new broadband resonance structure is confirmed by experiments.By using the analytic method proposed,the resonance frequency and the sound absorption coefficient are accurately calculated.Via increasing the soft tube length and combining a series of soft tubes,the frequency band of sound absorption is effectively widen.A new approach to reduce low-frequency and broadband noise is provided by using this structure,which lays a technical foundation for infrasound and very low-frequency noise control.