This title says it all, basically. I explain that acoustic foam does not block sound about 5 times a day to prospective customers wanting to know how to soundproof. The question invariably  comes back, “Why not? Then what the heck is it used for?”It’s not that I’m trying to ruin anyone’s day here – I would love to have foam that could stop sound from going through walls. I would sell a ton of it.  But physics is physics and the fact is that we at Acoustical Solutions are not going to sell anything to someone that has zero chance of meeting a customer’s expectations.Now, a lot of Audiophiles and people very familiar with the nuances of sound will say: “Well if you have a relatively small confined space with a given large sound source the waves will build up and potentially amplify certain frequencies due to modal responses of the shape of container – and therefore adding absorption to the inside of said confined space will indeed reduce overall dB from escaping into the environment

,” but that’s not the point, I say.The point I’m trying to make is that putting a few squares of 2” thick foam here and there on a partition wall in an apartment will not keep someone from hearing the other guy’s TV and sub woofer at 3 AM.  Even covering the wall 100% with 2” thick foam is not going to, to the extent of the person’s expectations, stop that sound from traveling right through the wall. Using acoustical foam is not how to soundproof.For instance, some speakers used to use foam as the speaker grille cover years ago. If foam is that great at blocking sound, then why do that? Or the old earphones on Walkman’s from back in the day (I’m showing my age here) – they had foam right over the head phone to make it more comfortable for the listener. The foam in both of those examples was not blocking the sound in any way. The sound just poured right through. Here’s the deal: absorption and blocking are two totally different things. I explain things better with analogies, if you have read any of my previous blogs you will be used to this by now.

The color white “reflects” all light, right?  And the color Black “absorbs” all light. What we perceive as white is simply just all colors of light mixed together, and what we perceive as black is the absence of all color.  Shine a flashlight at a bright piece of tissue paper and you will register a great deal of reflectivity. Shine the flashlight at a dark black colored piece of tissue paper and you will register very little reflectivity.However, being that it’s tissue paper, you put either the white or black paper up against the light and use a rubber band to totally cover the end of the flashlight with it, and you will register nearly the same amount of luminosity traveling through both colors of tissue paper. Maybe a tiny little less with the black…it’s not a perfect analogy. Splitting hairs aside though, the point is that sound does the same thing: It reflects off certain surfaces and it’s absorbed by other surfaces, in much the same way white reflects light and black absorbs light.

When you look at recording studios that have all this fancy foam all over the place, don’t make the assumption that it’s the foam that is blocking sound from going through the wall. jual ac portable low wattThey have added layers of mass and caulk and isolation to that wall first to block the sound from traveling through, then added the foam to reduce echoes in the room for various reasons.wiring diagram for goodman a c unitOne of the main reasons foam, or any acoustically absorbent material (baffles, banners, fabric wrapped wall panels, etc.), are used, is to reduce the average reverberation time in a room. car ac repair huntsville alA good example of a space that will benefit from adding acoustical absorption is a large gymnasium.

Here is an excerpt from a recent email exchange I had with a customer:ME: “Sound goes out from its source and goes until it has simply gone through enough air that it loses energy and falls below the background noise level or below the threshold for our hearing. If there happens to be a wall, floor, or ceiling in its way before it has gone through that certain amount of air, the sound will bounce right off and head in a different direction still looking for enough air to go through before it dissipates. The louder the sound, the more air (distance) it has to go through to dissipate. PA systems are a great deal louder than a person’s voice. If the sound hits a surface that is very hard and immobile, it will bounce the sound energy at nearly 100% efficiency, which means the sound from a persons voice over a PA system is literally bouncing around the room for about 5 seconds or so. That five seconds is the Reverb Time, or RT 60, of that room. People speak in a quick succession of vowels and consonants, so if the listener is hearing 5 or 10 vowel sounds still hanging in the air with 5 or 10 consonant sounds….all you hear is garble. 

Hanging Sound Baffles work because they are not 100% efficient at reflecting the sound – in fact they are nearly 100% efficient at NOT reflecting the sound. They are absorbing the sound reflections and therefore reducing the overall average Reverb Time. ”CLIENT: “So Matt, how do I actually go about blocking sound through a wall or ceiling or anything else?” That, unfortunately is a much bigger discussion. It takes mass, or weight, and layers of it that are mechanically disengaged from one another, and sealed up tight 100% with caulk and putties, and…etc. I actually have a previous blog entry that I wrote on the subject.As always, I welcome any comments or questions, feel free to contact me using the information below. Thanks and Happy Acoustical-ing!Contact Me for more information:Matt BoughanVirginia Territory Sales Manager800.782.5742 ext. 111Direct: 804.349.0051Contact Matt BoughanE-mail: shhong@kiost.ac.kr.AbstractThere is growing concern over plastic debris and their fragments as a carrier for hazardous substances in marine ecosystem.

The present study was conducted to provide field evidence for the transfer of plastic-associated chemicals to marine organisms. Hexabromocyclododecanes (HBCDs), brominated flame retardants, were recently detected in expanded polystyrene (styrofoam) marine debris. We hypothesized that if styrofoam debris acts as a source of the additives in the marine environment, organisms inhabiting such debris might be directly influenced by them. Here we investigated the characteristics of HBCD accumulation by mussels inhabiting styrofoam. For comparison, mussels inhabiting different substrates, such as high-density polyethylene (HDPE), metal, and rock, were also studied. The high HBCD levels up to 5160 ng/g lipid weight and the γ-HBCD dominated isomeric profiles in mussels inhabiting styrofoam strongly supports the transfer of HBCDs from styrofoam substrate to mussels. Furthermore, microsized styrofoam particles were identified inside mussels, probably originating from their substrates. Supporting InformationThe Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.est.5b05485.Materials and methods including mussel sampling according to substrate type, chemicals and reagents, HBCD analysis in styrofoam and mussels;