For the majority of people who have the need of soundproofing, it is usually after the walls are complete. At this point it may be all but impossible to remove drywall change electric sockets and such to install soundproofing within the wall. It should be noted that soundproofing is impossible to achieve unless in a total vacuum. Only percentages of reduction of noise are possible. This reduction is measured in decibels (dB). 10 db represents a 50% reduction or increase to the human ear.
Specifications when added to a standard wall:
Independent certified lab tested : STC 53
In 4000 Hz speech range test results indicated the treated wall produced a 67 dB reduction (which represents over 98% reduction in noise to the human ear)
This unique flexible mechanical isolation material allows the wall cover to be free to vibrate from sound waves which transforms sound energy into inaudible mechanical friction energy. This energy being isothermal/adiabatic.
Exterior Exposed Finish:
Preferable it should be covered with drywall and final finish on dry wall can be given as per interior requirement.
you may consider using an aesthetically pleasing paint, wallpaper or covering to go over the material. This will in no way reduce the soundproofing characteristics.