Patent ID: 8175311

Claim:
An electroacoustic waveguide system, comprising: an acoustic waveguide having an open end, a closed end, and an effective length; an acoustic driver having a first radiating surface to radiate sound waves into free air and a second radiating surface to radiate sound waves into the acoustic waveguide so that sound waves are radiated at the open end into free air that would ordinarily oppose radiation from the first radiating surface at a dip frequency; and a source of opposing sound waves positioned in the acoustic waveguide so that there is an acoustic null at the open end at the dip frequency so that combined radiation into free air from the first radiating surface and the open end is free from appreciable reduction in radiation at the dip frequency; wherein the acoustic driver is positioned at a distance substantially 0.25 L from the closed end of the waveguide, where L is an effective length of the waveguide.