Patent ID: 9749735
Date: 2017-08-29
CPC Classifications: H04R

Claim:
1. A waveguide for conducting sound that is generated by a loudspeaker that is acoustically coupled to the waveguide, comprising: a duct with an external wall, an interior opening circumscribed by the wall, a cross-sectional area, and an outlet, wherein the duct is sized to resonate at frequencies within an operating range of the loudspeaker or is tapered to provide impedance matching with the surrounding environment; and an air-adsorbent structure coupled to an inside of the external wall of the duct such that the air adsorbent structure lines at least a portion of the wall, wherein along the lined portion of the wall some but not all of the cross-sectional area is filled with air-adsorbent structure; wherein the apparent volume ratio of the air adsorbent structure is at least about 1.5.