A surround for protecting an acoustic device for sending and/or receiving acoustic signals positioned therein from impact as the surround is rolled along an interior surface of a fluid-containing pipeline, the surround comprising: a shell comprising an exterior segment configured to roll along the interior surface, the exterior segment defining at least one acoustic aperture configured to allow the passage of acoustic signals therethrough; and a lattice configured between the exterior segment and the acoustic device, the lattice comprising a plurality of unit cells, each unit cell defining an opening, wherein the plurality of unit cells are interconnected and define a plurality of openings, wherein the plurality of openings allow fluid to move between the interior of the surround and the exterior of the surround and enable the passage of the acoustic signals transmitted and/or received by the acoustic device such that the surround reduces the diminution of the quality and/or strength of the acoustic signals.