Understanding STC Rated Doors

There are a variety of use cases where STC rated doors, or soundproof doors would be useful. Some of those include construction sites, office rooms, libraries, exhibit halls, etc. But what exactly is an STC rated door? What does an STC rating mean and what are the important factors to look for when buying STC rated doors?

To help you understand more about what STC rated doors are and what goes into the STC ratings for these soundproof doors, we have put together a guide on how the STC scale works and how it relates to these doors.


What is STC?

Let’s start first with what exactly STC is. Sound Transmission Class is an integer rating based on how well a partition (such as a door or wall) reduces sound. STC is calculated by taking the Transmission Loss (TL) values tested at 16 standard frequencies divided by the range of 125 Hz to 4000 Hz and then plotted on a graph. The chart below will give you a better idea on what these STC ratings mean.

STC What can be heard
25      Normal speech can be understood quite easily and distinctly through the wall
30      Loud speech can be understood fairly well, normal speech heard but not understood
35      Loud speech audible but not intelligible
40      The onset of “privacy”
42      Loud speech audible as a murmur
45      Loud speech not audible; 90% of the statistical population is not annoyed
50      Very loud sounds can be faintly heard; 99% of the population is not annoyed.
60+    Superior soundproofing; most sounds inaudible

One key factor to consider while purchasing soundproof doors based on their STC rating is that it cannot solely be relied upon when trying to reduce noise from lower frequencies, such as bass drums or HVAC systems. This is because the scale does not start that low so there is no way to be 100% sure if a certain STC rated door will reduce noise from a lower pitched noise. If you are looking to reduce noise from these sources, consult with our acoustical experts who can help you find the perfect sound reducing door for you.



So, how does this relate to soundproof doors?

Now that you have a better idea on what STC ratings are and how the scale works, let’s relate this back to soundproof doors. This relationship is actually quite simple; STC ratings were merely a straightforward way to identify how effective a particular partition was at reducing the amount of sound that came through to the other side. STC is a universal scale that is easily understood by those in the industry and is the most practical way to identify soundproofing quality.


How to Buy STC Rated Doors

Buying STC rated doors can, sometimes, be a complex process. Depending on what your individual needs are, what the current sound levels are of the noise you wish to reduce and potential location-specific stipulations, it may be best to consult with an acoustical expert before making a purchase.

However, if you already know what type of STC rated door would best suit your soundproofing needs, check out eNoise Control’s selection of premium, high STC rated doors. eNoise Control STC rated doors, combine all the most important features of a soundproofing partition into one highly-effective and easy to install package.

To get started, give us a call at 888-417-1903 or send us an email to