Tunable acoustic absorber with micro deep hole array

We present a tunable acoustic absorbing system. Most of the conventional acoustic absorbers can absorb an only sound of a fixed frequency. We propose an acoustic absorbing system with a tunable compliance in order to absorb variable sounds. The developed system forms an array of Helmholtz resonators with a deep hole array by a X-ray lithography. Micro deep holes are effective at low frequency. The resonator has an air cavity whose volume is controllable so as to tune its resonant frequency to a desired frequency. This paper reports the characteristics of our developed acoustic absorbing system and our project status