Stc and oitc ratings. Confirm ratings for .

Stc and oitc ratings What is considered an acceptable rating for STC and OITC? The amount of nearby noise will typically determine what constitutes an acceptable STC and OITC rating. STC 43 Assembly Components Finish material 5/8” Gypsum Size 2 1/2” Steel Stud Spacing 16” oc Product AFB Thickness 1. 5” Acoustics Assembly Number: ISS-00 STC: 43 OITC: 28 Report No. This rating is most appropriate for comparing performance of interior partitions to be used between rooms where there is not strong low-frequency sound. If you need testing for these three sound ratings, Intertek can help. As with STC ratings, the higher the OITC number, the more sound resistant the product is. In fact, dual-pane windows with dissimilar glass can achieve STC ratings nearly as high, if not as high, as triple-pane or laminated glass. Widely used STC (Sound Transmission Class) measures frequencies from 125 Hz to 4000 Hz. One can expect that new norms will much more resemble the OITC approach. ] Discusses the acoustical properties of glass, methods of rating, such as STC and OITC, applicable standards and the relationship between glass and other glazing components in determining an overall rating. “Windows with a high STC rating typically have the same OITC rating as windows with a lesser STC rating, which can be a bit misleading. The STC (Sound Transmission Class) rating is a single-number rating system for interior building partitions and viewing windows used to categorize acoustic performance. 2. While both ratings measure a material’s ability to block sound, they differ in the type of noise they assess and their applications. 17. This rating is common in residential buildings with minimal soundproofing. Today, the OITC rating System is used to assess any barrier meant to block out low frequency sound. The OITC rating represents transmission loss results from 80 to 4,000 Hz using a different mathematical equation than the STC rating. The OITC is the preferred method of comparison of façade elements including roofs for blockage of exterior sounds. Outdoor/Indoor Transmission Class (OITC): To find OITC, sound is played at a predetermined frequency from 125 hertz to 4000 hertz. A receiver on the Phone: 888-815-9691. The TMS 302 Sound Standard provides minimum requirements for rating masonry walls for sound transmission class (STC) and outdoor-indoor transmission class (OITC) based on testing calibrated calculation procedures. Both OITC and STC indicate a wall’s ability to block the transmission of sound from one side of the wall to the other. J2247-13-303-11-R0 Insulation Included "Sound Transmission Class (STC)" and "Outdoor/Indoor Transmission Class (OITC)" ratings are for individual units based on independent tests and represent entire unit. Mar 23, 2017 · Background –STC Rating Testing • STC testing in accordance with ASTM E90 yields a curve showing sound transmission loss at 16 standard frequencies ranging between 125 –4,000 Hz, which are then averaged to find the STC value. If you have an STC 45 wall, this does not mean the wall stops 45 dB of sound. For both measures, the higher the number the better. STC ratings are the ONLY way to accurately compare various noise reduction products. Calculated by using the sound transmission loss values in the 80 to 4000 Hz range as measured in accordance with ASTM E-90(09). STC. They are logarithmic values and cannot simply be added. Jan 28, 2025 · As with STC, the higher the OITC number, the better the window or patio door unit keeps out unwanted noise. [3] The STC provides a standardized way to compare products such as doors and windows made by competing manufacturers. When evaluating the soundproofing needs of a space, it’s essential to understand the distinction between Sound Transmission Class (STC) and Outdoor-Indoor Transmission Class (OITC). Dec 31, 2024 · STC Ratings vs. A rating of 40 would likewise correlate with a volume reduction to approximately 1/16th of the original level (1/2)^4 = 1/16). If sound reduction is a priority, look for a window in the 30-35 STC range. What is a good OITC rating for windows? So, OITC is the ideal measurement for Peerless acoustic windows & doors. May 6, 2024 · ASTM E90, the same test method used for STC ratings, is used to calculate OITC ratings, but the OITC test includes a wider range of decibels between 80 Hz and 4,000 Hz to represent outdoor sounds such as car wheels on a road and engine noises. Double-hung windows are not available with triple-pane glass. The STC ratings allow accurate 'apple to apple' comparisons. Based on comparing written limited warranties of leading national wood window and wood patio door brands. 06 m W* n 0 792 612 Oct 21, 2013 · Definition of STC, Definition of SRI , Definition of OITC. Archtest results typically show IGUs in the 20s and 30s range Ratings derived from non-operable assemblies shall only be used for experimental purposes and are not part of this document. 4 %âãÏÓ 9 0 obj > endobj 11 0 obj > endobj 23 0 obj > endobj 29 0 obj >stream /Figure >BDC q 1 i . Study commissioned by Pella, 2021. You May 30, 2024 · STC is a widely recognized measure for sound insulation in windows and doors, focusing on human speech frequencies. 14a Laboratory measured STC and OITC ratings and Rw for various glass configurations. OITC measures lower frequency noise such as construction noises, car horns, and the sound The definitions of two ratings: Sound Transmission Class or STC and Outdoor-Indoor Transmission Class or OITC; The project’s design requirements and how they impact the glazing system, and; How to calculate an STC or OITC rating; STC versus OITC. The glass to center ratings, when tested to ASTM E1425 and ASTM E90, shall not be less than STC 37 and OITC 30. Acoustic glass windows offer some of the highest STC and OITC ratings available and are an excellent choice if you require the utmost in sound insulation. Lepage offers a variety of acoustic glass with high ratings. The Unit’s Loudness Professionals use the OITC rating System less frequently than the STC rating System. Mar 23, 2022 · The higher the STC rating, the more efficient the construction will be in reducing sound transmission within the frequency range of the test. The performance data below applies to an insulating unit constructed with two plies of glass and an air or argon filled space. 03. OITC differs from the STC rating in that the OITC was developed specifically to indicate transmission of noise from transportation Product Type Model IG Glass Type Sound Transmission Class (STC) Outdoor/Indoor Transmission Class (OITC) SS 25 21 DS 26 21 TS/DS (5mm/3mm) 32 27 Laminated 32 28 Sound Transmission Class (STC) rates how much sound is blocked from going through a product. The system includes many materials other than glass, including the framing, the glazing gaskets/sealants, insulating glass unit spacer Windows and doors can help block outside noises whether you live in the city or on a farm. The same process is used to determine STC ratings for doors. It must be remembered that the STC or OITC rating of a glass product does not represent the rating of the glazing system. See additional notes below data for specific The STC and OITC rating measures a window’s ability to block sound transmission. OITC, on the other hand, covers a broader frequency range (80 to 4000 Hz), including lower frequencies often associated with external noise. Ideal for airport applications or any building in cities or near highways. Rw ratings are similar to STC in that they follow familiar testing methods. How Does STC Differ From OITC? OITC stands for outside-indoor transmission class. Because most external noise is low-frequency, such as street traffic, construction, and low-flying planes, this is crucial. Both STC and OITC ratings inform your window or door selection based on sound insulation A: Based on our experience at the Architectural Testing Acoustical Laboratory, an OITC rating of 32 or STC rating of 40 is very difficult to achieve on a window with conventional 1" insulating glass. Sound transmission loss measurements may be conducted at some lower frequencies if requested in advance. The frequency content of many common exterior sounds closely resembles that used for the OITC The U. The door assemblies shall be tested in accordance with ASTM E 90. The STC and OITC ratings shall be calculated in accordance with ASTM E 413 and E 1332, respectively. Email: info@commercial-acoustics. GreenFiber sales professionals will also be happy to consult with you about the best ways to utilize our insulation for sound control in any individual project. S. OITC and Soundproofing Windows Jan 11, 2025 · The result is sound control over a greater range of frequencies and a significantly higher Sound Transmission Class (STC) rating than a window with standard dual-pane glass. com. The sum of the deficiencies below the contour curve must not exceed 32. The other is Outdoor/Indoor Transmission Class (OITC). If we assume that a branch of the United States Government, The University of Minnesota, The Minnesota Housing Authority, prominent acoustical engineers and several manufacturers of acoustical products are correct, a change of “1 STC” is equivalent to a change in loudness of “1 dB”. It uses a specific decibel (Db) range (80 Hz to 4000 Hz) which makes it a better measure for low sound frequencies such as road noise. •Outdoor-Indoor Transmission Class (OITC) is the STC ratings are used for windows, doors, walls and most building materials. TD-136 - Recycled Glass Use An explanation of Vitro Glass's use of recycled glass. Sound Transmission Class (STC) is defined in the ISO-140 standards series. Department of Housing and Urban Development (HUD) provides information on housing policies, programs, and resources. Address: 6301 N Florida Ave Tampa, FL 33604 The glass to exterior ratings, when tested to ASTM E1425 and ASTM E90, shall not be less than STC 38 and OITC 31. STC Reference Contour 1/3-Octave Band [Hz] 125 “Windows might have an excellent STC rating, but without a high OITC rating, low-frequency sounds can be intrusive,’’ Merck said. End Result: The test report will include the sound transmission loss values from 80 to 5000 Hertz, the STC rating and the OITC rating. The method compares a family of numbered contours with one-third octave band TL data covering the one-third octave bands from 125 Hz to 4000 Hz, inclusive. Sound Transmission Loss (dB) 43 Oct 14, 2014 · In the case of both STC and OITC ratings, a higher the rating, the better as it indicates that less noise is detectable. Jan 18, 2022 · STC Ratings Updated : 01/18/2022 by K. Single-pane units typically earn ratings between 26 and 28, while double-paned ones often range between 26 and 33. The STC (Sound Transmission Class) rating is a single-num ber rating system for interio r build ing partitions and viewin g windows used to catego rize acoustic performanc e. Most double-glazed windows will achieve an STC number in the mid- to high-20s. 2 Test Method. 50003 659. For example, if the transmitter played a sound at 60 decibels and the receiver picked up 30 decibels, the STC rating would be 30. *OITC is estimated based on this test. Implementation of the appropriate rating system is important because OITC and STC ratings are not linearly related, and the achievement of a strong STC rating does not necessarily correlate with a similar OITC rating. Nov 24, 2022 · Because OITC measures how well sound is blocked from the outside, it’s actually a superior rating system to STC when considering a window’s acoustical performance. STC Rating: The new GE Zoneline has an STC rating of 29. The Sound Transmission Class (STC) method assigns a single number rating to measured Sound Transmission Loss (TL) data obtained in accordance with ASTM E-90. However, since its invention is relatively new, having been created in 1990, it’s still not used as widely as the STC, which was developed in 1961. Here’s a quick guide to interpreting STC ratings: STC 25-30: Speech can be easily understood through the partition. OITC. 2 This classification requires data in one-third octave bands from 80 to 4000 Hz of sound transmission loss (TL) for outdoor-indoor transmission class (OITC), outdoor-indoor noise reduction (OINR(θ)) for outdoor-indoor noise isolation class (OINIC(θ)), or other data based on the rating definition for other ratings based on this classification. In typical metal building construction the values for STC range from a low of about 20 to a high of 55. Source: STCratings. “Sound reduction is becoming increasingly important for many different types of buildings, such as schools and religious facilities,” observed Tony Bouquot, MBMA’s general manager. STC 35-45: Loud speech is audible but less intelligible. An STC rating is an instrument measurement of how much noise is stopped. com Conclusion: A person cannot detect a change in loudness of +/- 1 dB (STC). May 22, 2022 · The window and door industry consider OITC ratings at least as important as STC (Sound Transmission Class) ratings. * * [The data and information set forth are based on samples tested and are not guaranteed for all samples or applications. Like the STC rating System, OITC measures sound intensity loss in decibels. The OITC rating is similar to the STC rating in that it uses ASTM E-90 TL data to derive a single number rating system that increases with increasing sound isolation ability. 2 Test Method The door assemblies shall be tested in accordance with ASTM E 1425. Similar to STC ratings, OITC ratings provide information on how well a barrier blocks sound, and should be taken into consideration as you shop for soundproofing How the OITC Rating is Measured. While you may be familiar with Sound Transmission Class (STC) ratings, there is another relatively new way of measuring sound transmission: Outdoor-Indoor Transmission Class (OITC). STC ratings for sound-reducing windows begin at about 32. UPDATED; TD-138 - Heat Treated Glass for Architectural It is very common for the results of ASTM E90 to be presented as single number ratings to make it easier to compare two PTACs. That being said, anything below an STC rating of 40 might garner comments about paper thin walls. It is an International Organization for Standardization (ISO) rating and part of the ISO 140 (Acoustic) family. Sound-dampening inter-layers reduce noise levels by up to 50%. While not as well known as STC, OITC is a more appropriate measure when comparing the true sound control performance of a window. 22. See written limited includes both STC and OITC ratings for steel and wood stud walls, considering both interior and exterior assemblies. Due to ongoing product changes, updated test results or new industry standards or requirements, this data may change over time. If a 105-decibel above ground subway only registers as 80 decibels after traveling through a Window or wall, the sound experiences a 25-decibel deficit. For more information on the STC and OITC rating of Andersen® products, please view the Performance Grade and Air Infiltrations for Andersen® Products. A typical dual-pane window has an STC rating of 25-30. The results express in decibels as opposed to the point system used to determine STC ratings and with weighting more towards low frequency performance. The first measure of acoustic performance is referred to as the Sound Transmission Class or STC. Mar 30, 2023 · Also, an acceptable STC rating for walls may be different from the acceptable STC rating for floors, depending on whether the walls are shared by a neighbor, or a room is directly beneath a kitchen with heavy traffic. This range is suitable for offices or moderately noisy environments. The OITC rating is never greater than the STC and can be as much as 17 points less than the STC for some assemblies. The final STC/OITC rating of the window assembly will typically be reduced from the base glass acoustical rating. J2247-13-303-11-R0 Insulation Included STC OITC Test Date Number Operating Style Series Numbers Tested Size OA Glass 1 Glass 2 Acoustical Ratings - Tuscany I V400 updated 09. Ensuring your building meets the proper project and building code requirements for STC, OITC, and IIC sound ratings can ensure that your building's space offers an environment that will be comfortable for occupants and not generate complaints. What Affects STC Ratings? STC ratings for windows vary depending on the glazing. How are STC and OITC Measured? Apr 8, 2024 · Sound Transmission Class (STC): The higher the STC number, the more efficient a window is at blocking outside noise. Selecting the right product for reducing sound coming in from a window is a lot different than soundproofing a bedroom to be used as a podcasting studio, for example. E413-87 in an acoustical wall. STC: This system has grown to be the most used and recognized method of comparing acoustic performance of building products in the industry—not Jun 20, 2023 · Understanding STC & OITC Ratings. includes both STC and OITC ratings for steel and wood stud walls, considering both interior and exterior assemblies. The final STC/OITC rating of the window assembly could vary because of the influence of the framing members and the construction of the window assembly. 751 614 -426. com Nov 25, 2022 · The difference between the sound level inside the window and the sound level outside the window, measured in decibels, is the STC rating. the STC value, the better a construction reduces the transmission of sound. To determine the specific STC ratings of glass and a OITC (Outdoor-Indoor Transmission Class) measures outdoor-to-indoor sounds, like traffic, airplane noise, and construction. Fiberglass bands from 125 Hz to 4000 Hz. Insulation Type STC. Glass size and glazing system will affect STC rating. The STC rating indicates the Aug 8, 2022 · 4. Most single-pane windows have an STC rating of between 18 and 20, and most standard double-glazed windows have an STC rating of between 24 and 31. Type STC OITC: Panel Doors: 29 27: Doors with Glass: 30 28: Doors with Mirror : 34 31 Type STC OITC: Fir 6-Panel: actual rating could vary. How the OITC Rating is Measured Like the STC rating System, OITC measures sound intensity loss in decibels. Topics covered include reference standards, definitions and notations, materials, construction, and methods to STC and OITC rating for concrete masonry and clay masonry assemblies OITC measures the ability of a product to reduce the overall noise of ground and air transportation. Mar 20, 2019 · It documents the ratings for sound transmission class (STC) and outdoor-indoor transmission class (OITC) on standard metal building ceiling and wall assemblies. What Is an OITC Oct 10, 2024 · Using STC/OITC Rating Systems when Selecting Products When it comes to soundproofing, there are many variables at play, most importantly of which is your specific needs. Outdoor-Indoor Transmission Class (OITC) rates how well a barrier blocks sound, with an emphasis on low-frequency noises such as bass-heavy music or a plane flying overhead. OITC* Frequency (Hz) 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500. Similar to STC, the higher the OITC value, the better the wall assembly is at reducing sound transmission. Board on Interior STC the sound transmission class (STC) and the noise reduction coeffi cient (NRC). Comparing STC and OITC Ratings of Different Window Types STC Rating To obtain the Sound Transmission Class (STC), read the TL of the contour curve at 500 Hz. The OITC rating system is mostly consulted when there are low-frequency sounds involved between 80 to 100 decibels that can't be calculated by the STC rating. To achieve these ratings and above, a dual window configuration with two sets of sash or a prime window with an exterior or interior storm panel product quotes and published STC/OITC and U-Factor ratings of leading national wood window and patio door brands. GE Zoneline has an OITC rating of 21. OITC (Outdoor-Indoor Transmission Class) is a more modern and “real world” test that includes sounds on the lower end of the spectrum, from 80 to 4000 Hz. Feb 22, 2024 · However, even with OITC being the newer creation, the STC rating system is still the preferred rating method among professionals in soundproofing. 14 − 10log 10 å f 10((L f-TL f +A f) / 10) Where: STC OITC Test Date Test Number Operating Style Series Numbers Tested Size OA Glass 1 Glass 2 Acoustical Ratings - Ultra I C650 updated 04. If a 105-decibel above ground subway only registers as 80 decibels after traveling See full list on ngctestingservices. Wall Assembly Acoustical Testing Results. advantage, including details on wall assemblies and their STC/OITC ratings. Notably, road noise is a lower frequency sound, so depending on the proximity to busy streets and interstate highways, it is important to consider the OITC rating and look for higher numbers. 24 Page 1 of 2 Due to continual product research and development, details listed are subject to change at any time Jun 17, 2019 · Reduction in sound based on OITC ratings of Pella Lifestyle Series windows to a single-pane wood or vinyl window with an OITC of 19. Please see the reverse side for a comparison of how our cellulose and 4-inch Sound Control Batts perform in PDF-1. Plastpro Doors STC and OITC Rating specify the STC or OITC that is required of the glazing system. OITC Ratings. Sound Reduction Index (SRI) is defined in ISO-140 (2012). Study of homeowner perceptions of leading national brands. A higher OITC demonstrates a door’s increased ability to prevent low-frequency sounds from entering the home. The ISO international rating (Rw) can also be calculated if requested in advance. Data is based on testing ~36" x 84" glass to ASTM E413-87 in an acoustical wall. Performance documents for altitude limits, NFRC ratings, center of glass, joining window load table, air infiltration, and more. To determine the specific STC ratings of glass and a STC EWR; OITC single hung; 2210 2211 2230 2230J 2270 picture window (slider frame) 2310 2311 STC Ratings - Trinsic Due to continual product research and Jul 30, 2024 · The Outdoor-Indoor Transmission Class (OITC) rating, calculated according to ASTM E1332, measures the capacity of a window or door to reduce the transmission of exterior noise to the interior of a building across the frequency range of 80 to 4000 HZ. Pim Foam or Dura**** OITC Test Date Test Number Intercept or Cardinal horizontal slider 6110 6111 6130 6130J 6170 size tested transmission, an OITC rating is designed to account for sound transmission from typical outdoor sounds which consists of frequencies lower than an STC rating. Confirm ratings for STC and OITC are standards that measure sound attenuation. Resource Alert: Find OITC and STC ratings for roof-ceiling assemblies on pages 111–112 of The SoundBook. The latest editions of the stan-. The glass to interior ratings, when tested to ASTM E1425 and ASTM E90, shall not be less than STC 38 and OITC 30. The two most common ratings for sound transmission loss are Sound Transmission Class (STC) and Outdoor Indoor Transmission Class (OITC). For example, if your neighbor has a subwoofer-equipped sound System, you may want to consider OITC ratings for all of your barriers, interior and exterior. Explore noise reducing windows and doors from Pella. Examples would be a 100 Series window Topics covered include reference standards, definitions and notations, materials, construction, and methods to STC and OITC rating for concrete masonry and clay masonry assemblies. But they also differ quite a bit: for example, Rw covers a larger frequency range than STC. For example, if your neighbor has a sub woofer-equipped sound System, you may want to consider OITC ratings for all of your barriers, interior and exterior. TMS 302-18 is adopted by reference in the 2021 International Building Code. 3. Intertek Testing Locations: Ratings derived from non-operable assemblies shall only be used for experimental purposes and are not part of this document. Oct 16, 2023 · acoustical ratings-->--> X 32 29 04/12/23 TL23-119 acoustical ratings not available for this glass combination glass combination X--> X 30 27 04/12/23--> X 34 29 12/14/22 OITC Test Date Test Number Intercept or Cardinal horizontal slider 6110 6111 6130 6130J 6170 size tested net 59" x 47" STC 29-34 X X <--32 Operating Style Series Numbers Glass OITC is a newer rating system developed specifically for measuring sound transmission of low- and mid-frequency noises through exterior walls. E413-87 in an acoustica l wall. STC (Sound Transmission Class) STC is a rating system that measures how well a building material or assembly can reduce sound transmission. Single Number Ratings •Most SNR (STC, EWR, R w) are calculated directly from the transmission loss spectrum of the assembly. best fits the data gives the STC rating. This data is accurate as of October 2018. Outdoor Indoor Transmission Class (OITC) Sep 21, 2018 · The OITC rating is used to measure the sound transfer between outdoor and indoor spaces. • However, because the actual sound transmission loss can vary widely across the STC 29 / OITC 20 R-10 Faced 202-96 Insulation Over the Purlins STC 32 / OITC 22 R-19 Faced Insulation Over the Purlins STC and OITC Ratings for Typical Metal Building Constructions Walls Roofs STC 54 / OITC 39 R-13 Faced 202-96 Insulation Over the Girts 3 5/8” Steel Studs on 24” Centers with R-11 Batts and 1/2” Gyp. J2247-13-303-11-R0 Insulation Included Oct 14, 2014 · interior window retrofits, laminated glass windows, oitc, sound control windows, sound ratings, stc Comments are off Sound ratings were developed by the American Architectural Manufacturers Association (AAMA) and the American Society for Testing and Materials (ASTM) to standardize the testing and rating of sound transmission for building Acoustical Guide – Determining Minimum STC Rating Figure 1. The STC rating has been in existence for many years and is based on speech sounds. For windows, STC ratings range from 18 to 38. The sound attenuation properties of a glazing type will be achieved with the plastic interlayer STC indicates how well an interior wall, exterior wall, door, window, or floor blocks noise. Outdoor-Indoor Transmission Class (OITC) Recently, a new single-number rating has The two rating systems used to measure the acoustical performance of windows and doors are OITC (Outdoor Indoor Transmission Class) and the STC (Sound Transmission Class). For both STC and OITC ratings, the higher the number the better the sound Rw is the alternative to STC and used by most of the world. Sound Transmission Class (or STC) is an integer rating of how well a building partition attenuates airborne sound. Below is a brief description of each rating system. What is an Outdoor Indoor Transmission Class (OITC) rating? An OITC rating is a single number rating calculated in accordance with standard ASTM E1332 using the to the same sound. Outdoor/Indoor Transmission Class (OITC) is a number rating of the sound transmission loss of a constructed assembly tested with lower frequencies to represent sound typical of modes of transportation STC OITC Test Date Test Number Operating Style Series Numbers Tested Size OA Glass 1 Glass 2 Acoustical Ratings - Trinsic I V300 updated 04. Caution: You cannot add STC ratings. This rating measures higher-intensity noise, such as heavy Nov 16, 2024 · It uses varying glass thicknesses and specialized lamination techniques to disrupt different sound frequencies. 24 Page 1 of 7 Due to continual product research and development, details listed are subject to change at any time 5 days ago · In the building products industry, there are two main rating systems used to communicate how well products block sound: Sound Transmission Class (STC) and Outdoor/Indoor Transmission Class (OITC). OITC Rating The Outdoor-Indoor Transmission Class (OITC) is calculated by subtracting the logarithmic One is Sound Transmission Class (STC). The maximum deficiency at any one frequency must not exceed 8. 24 Page 1 of 7 Due to continual product research and development, details listed are subject to change at any time Buildings exposed to a noise level of 65 dB L eq-1-hr during any hour of operation shall have building, addition or alteration exterior wall and roof-ceiling assemblies exposed to the noise source meeting a composite STC rating of at least 45 (or OITC 35), with exterior windows of a minimum STC of 40 (or OITC 30). Nov 4, 2016 · The OITC rating (referenced in ASTM E1332, Standard Classification for Determination of Outdoor/Indoor Transmission Class) is calculated from the following formula, using a logarithmic summation of individual third OB TL measurements: OITC = 100. When it comes to soundproofing, two key ratings need to be considered: STC (Sound Transmission Class) and OITC (Outdoor-Indoor Transmission Class). If you have an STC 33 wall and decide to add another sheet of drywall with an STC of 20 you do not get a finished wall with an STC of 53. This disparity is due to the fact that, when compared to STC, OITC gives more weight to lower frequencies. The STC measurement has been around since 1961, so for a long time, that was the only rating to measure how windows performed acoustically, in 1990 the OITC measurement came about as a way to rate outside noise. The STC or sound transmission class is a single number method of rating how well wall partitions reduce sound transmission. Glass siz e and glazing system will a˜ect STC rating. You might get something around STC 35. Ratings are categorized by product Series. Others include the sound transmission class (STC) and the noise reduction coefficient (NRC). Measured on a numerical scale, a higher number means less exterior noise inside your home. OITC differs from the STC rating in that the OITC was developed specifi cally to indicate transmission of noise from transportation sources. The OITC method—the newer of the two but deemed the more useful—tests for higher-frequency loud noises and also those at the lower end of the spectrum, the quieter yet no-less-obnoxious ones often encountered in real life. 501 re 306 396. Sep 14, 2021 · Conduct These Three Sound Ratings. Why is OITC Important? Outdoor-Indoor Transmission Class determines a product’s performance in eliminating or suppressing exterior noise. *OITC is estimate d base d on this test. duam zmqj nraxei mgwvzt bqrlhp dmsfrsu kefjy ipkx qrvf eoru dvxiu hwh cha klgf igwwkzmp