Noise absorbing structures and walls made therefrom

摘要

The structure has a membrane (10) which is sealed onto a fixed supporting shell (12) so the sound is directed onto the external surface of the membrane. Plates are positioned within the shell a short, modifiable distance from the membrane. Alternatively, there may be a closed chamber with a passage or a channel between two adjustable plates linking it to an inner chamber. The membrane may carry rods which enter fixed tubes closed at the lower end where they are attached to the shell. The internal volume between the membrane and the base (18) may be adjusted by an inflatable air-filled balloon or bellows (26) connected to the exterior by a hole (28). Electrical conductors or circuit boards are printed or positioned on the membrane.