An acoustical barrier, an aperture and a pipe or cable passing therethrough wherein the aperture has a number of radially extending slits which define a plurality of radial sectors which also extend from the aperture. One or more grooves are arranged in the sectors concentrically about the aperture to increase the radial flexibility of the sectors so that the sectors more closely conform with the shape of the pipe or cable passing through the aperture and thereby reduce the spacing between the slits and reduce the noise passing through the seal.