necessary; this is due to the use of cheap materials and the lack of acoustic design. This uneven reduction in sounds results in a muffled voice and sound passing through in an unnatural way. The DM filter uses membranes according to our patented membrane technology. Since the membrane is made of a breathable material, this leads to optimal filter breathing keeping the ear canal cool and providing all day comfort. The advanced diaphragm is tuned to maintain natural hearing while speech is clearly heard. Another characteristic of the membrane is the pressure regulating properties; this provides additional comfort during flight and therefore it is this ideal filter for use by flight crew and travelers. This DM filter is suitable for a wide range of applications, especially if the noise source is at a constant level throughout the frequency range. Users include; musicians, sound engineers, aircraft crew, production workers and racing teams.