Reducing the transmission of sound between occupancies may be accomplished through the use of sound dampening materials. Fiberglass or mineral batts placed in the spaces between wall studs will help to reduce unwanted sound. Filling the wall spaces with foamed-in-place insulation is another way to reduce sound. Applying a layer of sound deadening material to the studs before nailing up the gypsum wall board is an effective way to reduce sound.
Dense or heavy materials are excellent for sound proofing. Brick walls resist the passage of sound. Concrete blocks and poured concrete provide great sound proofing. Although these materials are practical as exterior walls in most environments they are not often used as interior walls in multiple story uses because of the weight they introduce to buildings. Increased interior wall weight requires heavier structures overall which increases building cost.
One of the most effective ways to sound proof between spaces is the use of separate staggered walls with space in between two rows of studs. This method can be used with wood studs in residential and light commercial buildings or those utilizing metal studs in fire rated structures. Sound vibrates one wall surface but is not transmitted to the other wall surface through a common wall stud.
Many structures such as hotels, apartments and condominiums with shared walls require the highest possible degree of sound proofing. Combining sound proofing materials and methods is the best way to deliver maximum sound proofing. Construction for such occupancies commonly uses staggered stud systems, foam or insulating batts in the wall spaces and sound deadening board applied under the gypsum wallboard. Special care must be taken to ensure that electrical boxes and wall perimeters are well sealed to prevent sound penetration between occupants.
Reducing sound within a given space is achieved by placing soft materials within the room that soak up sound. Studios for sound recording are the best example of this usage. Padded walls and suspended clouds of soft material prevent sound from reflecting back and forth in echoing patterns. Many products are available for absorbing sound.