{"id":240,"date":"2012-09-20T17:21:37","date_gmt":"2012-09-20T17:21:37","guid":{"rendered":"http:\/\/www.fiberlitetech.com\/blog\/?p=240"},"modified":"2022-03-17T18:32:51","modified_gmt":"2022-03-17T18:32:51","slug":"what-do-nrc-and-stc-mean","status":"publish","type":"post","link":"https:\/\/www.fiberlitetech.com\/blog\/what-do-nrc-and-stc-mean\/","title":{"rendered":"What Do NRC and STC Mean?"},"content":{"rendered":"<p>Technical terms like Noise Reduction Coefficient (NRC) and Sound Transmission Class (STC) can be somewhat confusing.\u00a0 While one measures the build-up of noise within a space, the other measures the sound transmission between spaces.\u00a0 It is important to understand the difference of these two ratings. (See demonstration of sound control for <a href=\"\/Fiberlite-Technologies-2nd.php?pagename=Homeowners-Sound-Control\">Cellulose vs. Fiberglass<\/a> Insulation.)<\/p>\n<p>The Noise Reduction Coefficient (NRC) measures the build-up of noise within a space.\u00a0 A single number index rating is used to measure the sound absorption of a material.\u00a0 Fiberlite\u2019s Cellulose Insulation products have an NRC rating from .75 to .82 depending on wall design, materials and applied density of the product.\u00a0 Simply put, FTI\u2019s Cellulose Insulation products will absorb 75% to 82% of the sound that it comes in contact with and will reflect 18% to 25% of the sound back into the space.\u00a0 However, NRC does not address a material\u2019s barrier effect.\u00a0 Nor, does it give information as to how absorptive a material is in the low and high frequencies.\u00a0 NRC is only the average of the mid-frequency sound absorption coefficients (250, 500, 1000 and 2,000 hertz) rounded to the nearest 5%.\u00a0<!--more--><\/p>\n<p>The Sound Transmission Class (STC) measures the sound transmission between spaces.\u00a0 A single number rating is used to measure the assembly\u2019s barrier effect.\u00a0 A higher STC rating blocks more noise from transmitting through a partition.\u00a0 Loud speech can be understood through an STC 30 wall but should not be audible through an STC 60 wall.\u00a0 Fiberlite\u2019s Cellulose Insulation products have a STC rating of 44 to 68 depending on the wall construction.\u00a0 STC ratings do not assess the low frequency sound transfer.\u00a0 It is based on performance with frequencies from 125 to 4,000 hertz (speech frequencies). The STC rating is a lab test that does not take into consideration weak points, penetrations, or flanking paths.<\/p>\n<p>Acoustical wall treatments with a high NRC can stop sound from reflecting back into the space and lowering the noise level within the space. \u00a0Improving the STC rating of a wall (wall cavity insulation, etc.) will reduce the noise transfer to the adjacent space.<\/p>\n<p>More than likely you will have a builder or architect that requires this information.\u00a0 The NRC and STC ratings information may be found on our submittal data sheets.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Technical terms like Noise Reduction Coefficient (NRC) and Sound Transmission Class (STC) can be somewhat confusing.\u00a0 While one measures the build-up of noise within a space, the other measures the sound transmission between spaces.\u00a0 It is important to understand the &hellip; <a class=\"more-link\" href=\"https:\/\/www.fiberlitetech.com\/blog\/what-do-nrc-and-stc-mean\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1000,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[6],"tags":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/posts\/240"}],"collection":[{"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/users\/1000"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/comments?post=240"}],"version-history":[{"count":3,"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/posts\/240\/revisions"}],"predecessor-version":[{"id":1320,"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/posts\/240\/revisions\/1320"}],"wp:attachment":[{"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/media?parent=240"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/categories?post=240"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fiberlitetech.com\/blog\/wp-json\/wp\/v2\/tags?post=240"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}