What are the STCs in Soundproofing Walls?

Ultimately soundproofing represents the dampening of a panel that withstands it from vibrating and hence prevents the transmittance of extensive quantities of sound energy.

To fully understand the concept of soundproofing walls, we need to know what "Sound Transmission Class" (STC) is. STC is just a way of gauging sound transmission loss through a wall, as instituted and determined by the American Standards and Testing Materials (ASTM). This is an industry standard that is recognized by architects, designers, manufacturers, contractors and distributors of acoustic building products. The greater the STC rating, the better the sound attenuation of the acoustic barrier will be. STC
is basically the average decibel loss through a barrier across an array of frequencies (from about 125Hz to 4Khz). For those of you who don't know what a decibel is, it is simply a measure of ‘‘how loud’’ a sound is. An STC rating is the average difference p roduced by a wall assembly, essentially measured in dB, between the sound in one area and the sound in an adjacent area over several frequency ranges (technically 1/3rd octave bands).

A lot of people are curious as to what is an acceptable STC rating for their wall? This depends upon what disturbances may be coming from adjacent rooms of course. The National Research Council of Canada conducted a comprehensive survey of condo residents to determine noise-unhappiness with actual STC ratings of
their walls. The outcome establishes that complaints were decreased with walls at 50 or better, and just about non-existent with STCs of 60 or above.