摘要 |
<p>An acoustic panel comprises a first cellular layer with cells having a first axis, a second cellular layer with cells having a second axis, and a perforated septum layer separating the first layer and the second layer. The cells of both layers have an end distal to the septum layer and an end which meets the septum layer, and the maximum diameter of the cells of the first layer is less than the maximum diameter of the cells of the second layer.</p> |