Sound insulation:
soundproofing is any means of reducing the sound pressure with respect to a specified sound source and receptor (noise control). There are several basic approaches to reducing sound: increasing the distance between source and receiver, using noise barriers to reflect or absorb the energy of the sound waves, using damping structures such as sound baffles, or using active antinoise sound generators.
http://en.wikipedia.org/wiki/Sound_insulation
The ability of building elements to reduce the sound level between internal spaces, or between outdoors and indoors. In HVAC systems: acoustical treatment of fan housings, supply ducts, space enclosures, and other parts of system and equipment to isolate vibration or to reduce noise transmission
http://www.new-learn.info/packages/clear/glossary/glosstoz.h...

Window unit:
A non-load bearing device to fill a hole in a wall, consisting of both frame & sash members.
http://woosterglass.com/index.php?page=glass-terms
A complete window with the frame, sash, weatherstripping, sash opening mechanism and, at the option of the manufacturer, screens and/or storm sash assembled as a complete and properly operating unit.
http://www.russellmillwork.com/glossary/