Attenuators are introduced that offer quiet, enhanced sound quality for interior of enclosures than previous devices. An acoustical rating system for the levels of sound propagation through glass windows/windshields is introduced for the building and construction industry. Just as windows and insulation have an R-value to define the temperature energy efficiency of the interior of a room, an A-Rating™ system would define the acoustical energy efficiency of an enclosure space. In the summer, the higher the R-value, the less cool air that escapes a room through a window (and the less heat that penetrates into the interior), thus keeping the room cooler with less energy. Similarly, the higher the A-Rating™ of a window, the less noise that propagates through, maintaining lower levels of sound in the interior of an enclosure, creating a more harmonious, acoustically energy efficient room for enhanced health, preventing sleep interference, speech interference, and maintaining adequate levels of safety according to EPA and OSHA standards. The A-Rating™ system can help set standards for bearable and unbearable windows for a particular house, building, shopping store, restaurant, vehicle-cabin, fuselage cabin, locomotive/train/subway cabin, hotel, apartment, airport, library, museum, or any other enclosure, for a particular area or jurisdiction.