Abstract: The present sound barrier double-pane window includes panes wherein each pane is of a different thickness or a different density or a combination thereof. Since panes of different thicknesses or densities block or dampen different sounds, the double-pane window provides a quieter interior environment than a conventional double-pane window. The present sound barrier window also includes a peripherally mountable gasket with multiple peripheral ribs and cusped, pane-receiving surfaces to provide a sound-deadening seal between the exterior and interior environments.