摘要 |
A panel (1) including a substantially air impermeable membrane layer (3) and a layer (5) having apertures (6) therein, wherein each portion of the membrane layer (3) which overlies an aperture (6) defines a diaphragm (9) which is able to vibrate in response to sound waves incident on the membrane layer (3) and thereby absorb at least part of the sound waves' energy, at least some of the apertures (6) being arranged in clusters (11) whereby the greatest distance between adjacent apertures within a cluster (11 ) is less than the distance between (i) any one of the apertures (6) within the cluster (11) and (ii) any aperture (6) outside of the cluster (11), each region of the panel (1) defined by an outer periphery of a cluster (11) forming a resonance absorber (13) which is able to vibrate in response to sound waves and thereby absorb at least part of the sound waves energy, wherein at least one resonance absorber (13) is able to provide sound absorption at a frequency which is different to the frequency of resonance of at least one of the individual diaphragms (9). |