Home Cinema Sound Isolation - November 16th, 2008
No discussion of the quality of sound in a dedicated home cinema would be complete without a brief discussion of how to keep unwanted sound from entering a room, or how to keep the wanted sound in, so as not to disturb the pleasure of people inside or outside the home cinema.
The first thing to note is that just because a material is good absorber of sound doesn’t mean that it is a good isolator of sound. In fact most absorbing materials are terrible at sound isolation for home cinema installations. This is because, in the sound isolation case of a home cinema system, we are interested in the amount of sound that travels through a structure than the amount that is absorbed by it.
A poor value of sound isolation would be around 20 db yet it corresponds to only one hundredth of the sound being transmitted. A good absorptive acoustic panel with an absorptive coefficient of 0.9 would let one tenth of the sound through, which corresponds to a sound isolation of only 10 db! For hi-end home cinema installations we are more interested in sound isolations of 40 db as a minimum, so absorption is clearly not the answer.