Abstract: The present invention is a waveguide device having a body of molded, foam plastic with a speaker end and an open end and an even number of segments with a flat surface in a plane parallel to the speaker end. The segments have inside wall surfaces which flare increasingly outwardly from the speaker, and these inside wall surfaces have a speaker end length, L.sub.1, determined by the following formulas, L.sub.1 minimum=0.7.times.w.sub.s /0.0012 g/cm.sup.3 .times.1/A.sub.SE, and L.sub.1 maximum=1.2.times.w.sub.s /0.0012 g/cm.sup.3 .times.1/A.sub.SE, wherein L.sub.1 is a straight line length of the lower portion of the segment wall surface, w.sub.s is the weight of a speaker cone in grams/cm.sup.3, and A.sub.SE is the cross-sectional area of the speaker end in square centimeters. The waveguide body also includes an end plate with a speaker face and anchor inserts for attachment of a speaker thereto. The anchoring inserts are embedded in the waveguide body.