Maybe your neighbor told you that you needed sound absorption panels in your home theater and you didn’t want to ask. Maybe you have a big office with lots of people working in it and the boss told you to go buy some Sound Absorption materials or do the acoustic / absorption treatment in your office and then without further explanation.
The easiest way to understand this is with an analogy: An ocean wave comes in off the ocean, rolls in and hits a big flat concrete storm wall, its going to bounce right off of it and head back out to sea looking just like it did coming in. That is what a reflective panel would do, or drywall would do, or concrete…or anything hard and flat would do to a sound wave.
Now say a wave comes in off the ocean and hits a marshland with a bunch of reeds and grasses and muck. The wave is going to hit all those hundred billion little things which move around and dissipate its energy nearly completely and so the wave disappears. That’s what an absorptive acoustical panel will do to a sound wave.That’s about it.
NRC RATING I can’t just leave it at that though, if you’re so inclined to learn more, lets continue! X amount of sound hits the panel, and then a smaller percentage of that sound reflects off. How to compare apples to apples in terms of different Acoustically Absorbent Materials? Absorptive things in the world have a number called the NRC rating, or the Noise Reduction Coefficient. it doesn’t matter to the sound what an Absorptive panel is made of or what its wrapped in or any of that stuff. There is no guess work with this, the NRC rating is the rating. For instance, an NRC rating of 0.75 means that 75% of the sound is being absorbed (as averaged across the frequencies, more on that later) and 25% is being reflected back. NRC 0.85, 85% absorbed, 15% reflected.Etc.
AND NOW THE MOST IMPORTANT THING TO REMEMBER: Acoustically Absorbent panels DO NOT stop the sound from going through a wall. They are for reducing echoes within the room they are placed in, only. Things that STOP sound from going through a wall have an STC rating. This is entirely different class of materials utilizing much different principles of physics to block sound waves.
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