Editing Soundproofing (section)

== Applications ==

=== Residential ===
Residential sound programs aim to decrease or eliminate the effects of exterior noise. The main focus of a residential sound program in existing structures is the windows and doors. Solid wood doors are a better sound barrier than hollow doors.<ref>{{Cite web|url=http://www.stuff.co.nz/life-style/home-property/88589100/how-to-soundproof-your-noisy-apartment|title=How to sound-proof your noisy apartment|website=Stuff|access-date=2017-02-05|archive-date=2017-02-13|archive-url=https://web.archive.org/web/20170213094051/http://www.stuff.co.nz/life-style/home-property/88589100/how-to-soundproof-your-noisy-apartment|url-status=dead}}</ref> Curtains can be used to dampen sound, either through use of heavy materials or through the use of air chambers known as [[Honeycomb structure|honeycomb]]s. Single-, double- and triple-honeycomb designs achieve relatively greater degrees of sound damping. The primary soundproofing limit of curtains is the lack of a seal at the edge of the curtain, although this may be alleviated with the use of sealing features, such as hook and loop fastener, adhesive, magnets, or other materials. The thickness of glass will play a role when diagnosing sound leakage. [[Double-pane window]]s achieve somewhat greater sound damping than single-pane windows when well-sealed into the opening of the window frame and wall.<ref>{{Cite news|url=https://www.acousticalsurfaces.com/soundproofing_tips/html/multi_familybuild.htm|title=Noise Control in Multi-Family Residential Buildings|work=Acoustical Surfaces|access-date=2017-07-10|language=en-US}}</ref>

Significant noise reduction can also be achieved by installing a second interior window. In this case, the exterior window remains in place while a slider or hung window is installed within the same wall openings.<ref>{{cite web|last1=Camtion|first1=Eros|title=What is more effective between active noise cancellation and soundproofing ?|url=https://setiathome.berkeley.edu/team_display.php?teamid=210294|publisher=berkeley.edu}}</ref>

In the US, the FAA offers sound-reducing for homes that fall within a noise contour where the average sound level is {{val|65|ul=dB SPL}} or greater. It is part of their Residential Sound Insulation Program. The program provides solid-core wood entry doors plus windows and storm doors.<ref>{{Cite news|url=http://www.chicagotribune.com/news/local/breaking/ct-midway-sound-proofing-getting-around-0130-20170129-story.html|title=City wants more Midway-area homeowners to sign up for soundproofing|last=Wisniewski|first=Mary|newspaper=chicagotribune.com|language=en-US|access-date=2017-02-05}}</ref>

=== Ceilings ===
[[File: Ceiling Soundproofing.jpg|alt=Apartment Ceiling Sound Soundproofing, Soundproof Sheetrock, Resilient Isolation Channel, Viscoelastic Compound, Sound Proof Insulation|thumb|Apartment ceiling soundproofing]]

Sealing gaps and cracks around electrical wiring, water pipes and ductwork using acoustical caulk or spray foam will significantly reduce unwanted noise as a preliminary step for ceiling soundproofing. Acoustical caulk should be used along the perimeter of the wall and around all fixtures and duct registers to further seal the treatment. [[Mineral wool]] insulation is most commonly used in soundproofing for its density and low cost compared to other soundproofing materials. [[Spray foam]] insulation should only be used to fill gaps and cracks or as a 1-2 inch layer before installing mineral wool. Cured spray foam and other [[closed-cell foam]] can be a sound conductor. Spray foam is not porous enough to absorb sound and is also not dense enough to stop sound.{{citation needed|date=August 2021}}

An effective method to reduce impact noise is the "resilient isolation channel".<ref>{{Cite book|last=Long|first=Marshall|url=https://books.google.com/books?id=XTYTAAAAQBAJ&q=Resilient+Isolation+Channel&pg=PA579|title=Architectural Acoustics|date=2014-02-05|publisher=Academic Press|isbn=978-0-12-398265-0|language=en}}</ref> The channels decouple the drywall from the joists, reducing the transfer of vibration.

=== Walls ===
Mass is the only way to stop sound. Mass refers to drywall, plywood or concrete. [[Mass-loaded vinyl]] (MLV) is used to dampen or weaken sound waves between layers of mass. Use of a viscoelastic damping compound<ref>{{Cite book |last1=Chakraborty |first1=Bikash C. |url=https://books.google.com/books?id=abzLDwAAQBAJ&q=viscoelastic%20damping%20compound&pg=PR9 |title=Polymers for Vibration Damping Applications |last2=Ratna |first2=Debdatta |date=2020-01-31 |publisher=Elsevier |isbn=978-0-12-819253-5 |language=en}}</ref> or MLV converts sound waves into heat, weakening the waves before they reach the next layer of mass. It is important to use multiple layers of mass, in different widths and densities, to optimize any given soundproofing treatment.<ref>{{Cite web |url=https://www.fhwa.dot.gov/ENVIRonment/noise/noise_compatible_planning/federal_approach/audible_landscape/al04.cfm |title=4. Physical Techniques to Reduce Noise Impacts - The Audible Landscape: A Manual for Highway Noise and Land Use - Federal Approach - Noise Compatible Planning - Noise - ENVIRonment - FHWA |website=[[Federal Highway Administration|Federal Highway Administration (FHWA)]] |access-date=2020-02-13}}</ref> Installing soundproof drywall is recommended for its higher [[sound transmission class]] (STC) value. Soundproof drywall in combination with a viscoelastic compound may achieve a noise reduction of STC 60+.

Walls are filled with mineral wool insulation. Depending on the desired level of treatment, two layers of insulation may be required. Outlets, light switches, and electrical boxes are weak points in any given soundproofing treatment. Electrical boxes should be wrapped in clay or putty and backed with [[Mass-loaded vinyl|MLV]]. After switch plates, outlet covers and lights are installed, acoustical caulking should be applied around the perimeter of the plates or fixtures.

=== Floors ===
{{Unreferenced section|date=September 2021}}
Decoupling between the joist and subfloor plywood using neoprene joist tape or u-shaped rubber spacers helps create soundproof flooring. An additional layer of plywood can be installed with a viscoelastic compound. [[Mass loaded vinyl]], in combination with open-cell rubber or a closed-cell foam floor underlayment, will further reduce sound transmission. After applying these techniques, hardwood flooring or carpeting can be installed. Additional area rugs and furniture will help reduce unwanted reflection within the room.

=== Room within a room ===
{{Unreferenced section|date=September 2021}}
A room within a room (RWAR) is one method of isolating sound and preventing it from transmitting to the outside world where it may be undesirable.

Most sound transfer from a room to the outside occurs through mechanical means. The vibration passes directly through the brick, woodwork and other solid structural elements. When it meets with an element such as a wall, ceiling, floor or window, which acts as a [[sounding board]], the vibration is amplified and heard in the second space. A mechanical transmission is much faster, more efficient and more readily amplified than an airborne transmission of the same initial strength.

The use of [[acoustic foam]] and other absorbent means is less effective against this transmitted vibration. The transmission can be stopped by breaking the connection between the room that contains the noise source and the outside world. This is called acoustic decoupling.

===Commercial===
Restaurants, schools, office businesses, and healthcare facilities use architectural acoustics to reduce noise for their customers. In the United States, [[OSHA]] has requirements regulating the length of exposure of workers to certain levels of noise.<ref>{{cite news|url=https://www.nytimes.com/2012/07/20/nyregion/us-standards-on-workplace-noise-trail-those-of-other-countries.html?_r=1|title=U.S. Standards on Workplace Noise Trail Those of Other Countries|work=[[The New York Times]]|date=20 July 2012|last1=Buckley|first1=Cara}}</ref>

For educators and students, improving the sound quality of an environment will subsequently improve student learning, concentration, and teacher-student inter-communications. In 2014, a research study conducted by Applied Science revealed 86% of students perceived their instructors more intelligibly, while 66% of students reported experiencing higher concentration levels after sound-absorbing materials were incorporated into the classroom.<ref>{{Cite news|date=2014-12-08|title=Boosting Students' Learning With Soundproofing|language=en-US|work=[[The Wall Street Journal]]|url=https://online.wsj.com/articles/boosting-students-learning-with-soundproofing-1418061926|access-date=2021-05-20|issn=0099-9660}}</ref>

=== Automotive ===
[[File: Vehicle damping soundproofing.png|thumb|663x663px|Spatially averaged particle velocity spectra (left) and broadband colormaps of a car floor without (middle) and with (right) a damping treatment]]

Automotive soundproofing aims to decrease or eliminate the effects of exterior noise, primarily engine, exhaust and tire noise across a wide frequency range. A panel damping material is fitted which reduces the vibration of the vehicle's body panels when they are excited by one of the many high-energy sound sources in play when the vehicle is in use. There are many complex noises created within vehicles which change with the driving environment and speed at which the vehicle travels.<ref>{{cite web|url=http://www.carinsulation.co.uk/page/how-to-reduce-car-noise-improve-car-soundproofing|title=Mr|website=Car Insulation UK|publisher=CIUK|last1=Neale|first1=Paul|access-date=12 February 2015}}</ref> Significant noise reductions of up to 8&nbsp;dB can be achieved by installing a combination of different types of materials.<ref>{{cite web|url=http://www.hometheaterhifi.com/volume_10_2/car-audio-sound-deadening-6-2003.html|title=Introduction to Car Audio: How to Tame That Road Noise|publisher=Secrets of Car Audio}}</ref>

The automotive environment limits the thickness of materials that can be used, but combinations of dampers, barriers, and absorbers are common. Common materials include felt, foam, polyester, and [[polypropylene]] blend materials. Waterproofing may be necessary depending on the materials used.<ref>{{Cite book| title=UK Thinsulate literature|url=http://solutions.3m.com/3MContentRetrievalAPI/BlobServlet?lmd=1377607925000&locale=en_WW&assetType=MMM_Image&assetId=1361732207508&blobAttribute=ImageFile}}</ref> Acoustic foam can be applied in different areas of a vehicle during manufacture to reduce cabin noise. Foams also have cost and performance advantages in installation since foam material can expand and fill cavities after application and also prevent leaks and some gases from entering the vehicle. Vehicle soundproofing can reduce wind, engine, [[Roadway noise|road]], and tire noise. Vehicle soundproofing can reduce sound inside a vehicle from five to 20 decibels.<ref>{{Cite web|url=http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_08d0/0901b803808d007a.pdf?filepath=automotive/pdfs/noreg/299-51728.pdf&fromPage=GetDoc|title=DOW Automotive Systems: BETAFOAM™ acoustic foams|website=dow.com|access-date=2017-05-26}}</ref>

Surface-damping materials are very effective at reducing structure-borne noise. Passive damping materials have been used since the early 1960s in the aerospace industry. Over the years, advances in material manufacturing and the development of more efficient analytical and experimental tools to characterize complex dynamic behaviors enabled the expansion of the usage of these materials to the automotive industry. Nowadays, multiple [[viscoelastic]] damping pads are usually attached to the body in order to attenuate higher-order structural panel modes that significantly contribute to the overall noise level inside the cabin. Traditionally, experimental techniques are used to optimize the size and location of damping treatments. In particular, laser vibrometer-type tests are often conducted on the body in white structures enabling the fast acquisition of a large number of measurement points with a good spatial resolution. However, testing a complete vehicle is mostly infeasible, requiring evaluation of every subsystem individually, hence limiting the usability of this technology in a fast and efficient way. Alternatively, structural vibrations can also be acoustically measured using particle velocity sensors located near a vibrating structure. Several studies have revealed the potential of particle velocity sensors for characterizing structural vibrations, which accelerates the entire testing process when combined with scanning techniques.<ref>{{Cite book| title=Designing the damping treatment of a vehicle body|url=https://www.microflown.com/assets/uploads/Publications/AAC_2018_Designing-the-damping-treatment-of-a-vehicle.pdf}}</ref>

====Noise barriers====
[[File:Shinkansen Noise barrier(concrete board standard type).jpg|thumb|Noise barrier alongside a railway line in Japan]]
{{Main|Noise barrier}}

Since the early 1970s, it has become common practice in the United States and other industrialized countries to engineer [[noise barrier]]s along major highways to protect adjacent residents from intruding [[roadway noise]]. The [[Federal Highway Administration]] (FHWA) in conjunction with State Highway Administration (SHA) adopted Federal Regulation (23 CFR 772) requiring each state to adopt their own policy in regards to abatement of highway traffic noise.<ref>{{Cite web|url=http://roads.maryland.gov/index.aspx?PageId=827&d=114|title=Sound Barriers Guidelines - Highway Traffic Noise|website=roads.maryland.gov|language=en|access-date=2017-07-10}}</ref> Engineering techniques have been developed to predict an effective geometry for the noise barrier design in a particular real-world situation. Noise barriers may be constructed of wood, [[masonry]], earth or a combination thereof.