STC or sound transmission class is a rating system that compares how well building materials attenuate sound waves. These building materials include partition boards and other building materials. People normally consider STC ratings when they are constructing a structure where the reduction of sound is critical. For example, a recording studio needs to cancel out any outside noise to improve the quality of recordings. For this reason, it is impossible to build a studio without considering the STC ratings of the materials that you are using. Here is what you need to know about STC ratings.

Sound wave illustration. Voice sound assistant


The story of the STC rating system dates back to the sixties when it was introduced in the construction industry. As the construction of special structures increased, there was a need in the industry to regulate and compare materials used in terms of their ability to conduct sound. Apart from this, there was also the need to create a single standard that would be used across the United States. This is how the STC ratings came to be. Outside the United States, a similar system referred to as the Sound Reduction Index (SRI) is common.

How it is Measured

STC essentially measures the loss of sound transmission when sound waves go through a building material at various frequencies. Experts take two rooms which are designed as the source and receiving rooms. The rooms are divided by a partition made with the material whose STC rating is being tested. Using a variety of one-third octave band frequencies, the sound pressure between the two rooms is then compared. Typically, these frequencies will range between 125 Hz and 4000 Hz. The transmission loss of the partition is then measured at each of the bands.

How STC Ratings Work

The STC ratings of the material that you want to use is largely determined by the sound that you are trying to cancel out. The higher the rating is, the more sound that will be blocked. Apart from studios and a few other specialist structures, most other facilities do not require that level of noise cancellation. Conversely, if you play loud music (such as in a nightclub), you might consider renovating your premises to incorporate materials with high STC ratings. This way, you get to avoid potential noise violation problems. To get a better idea of STC ratings, a rating of 25 will probably let through a lot of sound. You will likely be able to hear and understand soft-spoken speech through the material. A rating of 60+ is considered soundproof and very little noise makes it through building materials of this rating.

At Materials Inc., we have a variety of building materials that come with different STC ratings for you to choose from. Our high-quality doors, wood panels, and decorative veneers are top-class and designed to give your building a splendid look. Get in touch with us today for a quote.

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