A common question is how much noise can actually be reduced by soundproof curtains. Before we can answer this however we must look at a term used to rate soundproofing materials like curtains, drywall, and windows. STC or also known as Sound Transmission Class is a rating of how well airborne sound is eliminated by the object in question. In other words, it can approximately tell you how much decibel reduction in noise you will get. We’re going to dive into a bit more detail than we normally would in this post so just be warned it may not make as much sense the first time through.
Quick decibel levels comparison
20dB – Watch Ticking
30dB – Whisper
60dB – Normal Conversation
70dB – Busy Street
90dB – Lawn mower
Drywall, windows, and noises
While in your house a typical layer of drywall with no insulation you’re looking around an STC of 30. This is also known as a paper thin walls because a person on the other side of the wall can hear you talking. So take a normal conversation decibel level of 60dB minus STC of 30 which you’re left with 30dB. Note that different frequencies can affect how much noise is actually reduced. As for windows a single-pane glass window will have an STC of between 20-25 which is doesn’t provide as much sound reduction as one would hope.
The top of the line industrial strength soundproof curtains can have a STC rating of up to 35. Unless you’re looking to really stop the noise and spend the money you unfortunately will have to settle for living room curtains which won’t provide as great of an STC rating. A really good set of curtains will probably have a STC rating of up to 15 while you’re most likely going to get between 5-10. Now this may not seem a lot at first but your perception of increases or decreases in decibel levels can weigh in on how much noise is actually being reduced. Plus of course the more layers of noise reduction materials you setup between you and the problem the decibel levels can only go down.
Looking at a quick example of a noisy street, having 70dB can be reduced on average by 20 by a window and then again by 10 by curtains. You’ve reduced the noise down to almost a whisper which is more enjoyable to sleep to though you can reduce it even more with foam, double-pane windows, and an additional set of curtains.