I always have been reading on books that Helmholtz resonators are great absorbers on a small frequency range. Its effect is given by the air inside the box which is acting like a spring and the dissipation of energy comes from the “neck” of the box. So basically mostly say it is similar to a mass-spring system but I would say that this can be thought like a mass-spring system with a dumper (neck effect).
Well, then I also found on books that Helmholtz resonators are very common in our life. A bottle is a very simple Helmholtz resonator. If you blow into it with its natural frequency the resonator will resonate making a sound with the frequency of its first mode.
So here my curiosity: I m not able to see the Helmholtz resonator like something that reduce the energy into the room since when it is forced by its resonant frequency it starts to sound increasing the sound.
Is there anyone which can solve my doubt? :)