The suppressor (1) has a curvature with convex and concave sides (3,4) on a cover plate (2). The plate fits between the lips and teeth to cover the gaps between the teeth. The cover plate can have a resilient retainer membrane (7) on its rear face. The membrane can be positioned in the central area of the cover plate and can have a thinner cross section than the cover plate. The membrane can be curved towards the convex side of the cover plate.
