And not many fake the testresults by using a high pitched sound like the horn to show how good this exact high sound is beeing dampend instead of showing a range of frequencies. If he would have done that by playing a song instead of that high sound AND had a speaker that could produce half decent base, this test would have shown the opposite result. Dont be fooled. Im not saying this product is bad for what it can do BUT this test was crazy biased.

@@nitromusik9275 wow your comment is such an eye opener, thank you so much for taking the time to sharing your knowledge to keep us better informed.

@@nitromusik9275 Yeah I hate all these tests you see where they're just dampening high frequency sounds that aren't going to be traveling through walls.

@@dylanj8676 but don't they use this in cars to dampen the bass? How would you like to see the test go?

@@MrHarbinged This won't help the really low frequencies in a building because that travels through the structure. I can't speak about how much MLV does in cars, but I would imagine it's airtightness of the doors and windows that does the most work there. The MLV is great for high frequencies like we've seen in the video, but when you get down to like 250 Hz it's way less effective. For reference a lot of 2 lb/sf MLV at 1 KHz attentuates around 30 dB. 250 Hz is somewhere around 15 dB. It's like a third as effective (10 dB difference is perceived as double the level, 20 dB would be half as much isolation as 30 dB, and 10 dB is half as much as 20dB, so 15 is approximately a third). That means you'll still hear a lot of noise bleed through shared walls and floors. If a kid is playing ball in the apartment next door or kids are running around you'll still hear it. The only actually solution to super low frequencies is proper isolation, which means decoupling (as in don't live in a place with shared walls) and having thick walls and making everything as air tight as possible. There's a reason proper recording rooms are airtight with double doors and a decoupled "floating" floor. And on the subject of cars, if a car stereo is turned up really loud you will absolutely hear the music even with windows up, it'll just be muffled because the bass frequencies aren't being attenuated much. That's how hard it is to deal with low frequency noise. What they should be doing is a test using different frequencies in different octaves. Not something way higher than the noise people are looking to block.

I agree. Notice when he held them snug the db rating was lower. had he done that across the board would there have been a more accurate comparison of the performance of the different weights/thicknesses of MLV?

You are absolutely correct my friend. And add onto that the fact that he is playing an air horn as the control signal. It would be much more informative if he played specific frequencies using a tone generator and calibrated the volume of each said frequency according to the speakers ability to produce them. Then you would be able to chart a somewhat more accurate performance of these materials. It’s a shame when people selling a product don’t understand the field of science that it exists in. I’m sure he’s a good guy but this is just silly.

that's eeeexactly what I was thinking! Good on ya Keith!! This video literally annoyed me. @@keithblackmore9

Careful though, I’m pretty sure the difference could be related to the seal at the bottom of the boxes, since the 2 lb box was much quieter for a split second when he pressed down on it which suggests a leak at the bottom

Yes, lower frequencies are the source of many complaints.

Not that great, for the lower stuff you need mass like bricks or thick concrete.

No, its diminishing effect

what materials are best for reducing low frequency? isolation clips? quiet rock drywall?

This material is best used in conjunction with a double stud wall to maximize both high and low frequency leakage reduction

To me it looks like he might have set the 2lb box a little too far to the left, thus leaving an air gap by the box being over the edge.

Much more, sound is still escaping from the tiny air holes where the box and the foam meet

But producing that seal in real live will be hard wont it?

He wasn't lining up the box with the bottom properly.

Headphones are worth there weight in gold. Use a headphone system with a limiter, and save your hearing for life.

let alone the frequency characteristics the applied filter on the sound meter had :D

the box just wasnt airtight

Good video, shame about the lack of feedback from the creator

@@dabeast9671 That could explain it.

airhorn by itself is about 92db half pound MLV = approx 82.4db before he started talking .75 MLV = approx 82.7db 1 pound MLV = approx 76db 1.5 pound MLV = approx 69.9db to 70db 2 pound MLV = 66db at 4:37 you can see it. He explained in the beginning that these boxes are not perfect. You can see him pushing down on the box to create a tighter seal between the box and the base.

staples

Staples probably. Velcro could work,but then you have to put part of the velcro on the wall anyway, whick you'll probably have to staple, and attach it to the MLV which will require an adhesive. So just use staples. But there's no point in attaching it to an existing wall. It's supposed to go in the structure, not on it.

He put the 1.5 in a spot where there were less air gaps, and with the 2 pound he accidently put it where there were a little more air gaps, this should have been a common sense answer but if people dont know how sound works would ask this exact question, so in this case the 2 pound will work REALLY good for sound proofing

note when he put it on and pressed down it went down to 65 db, then he lifts up and the left side is slightly off the base thus letting sound out -- the base should have been built slightly raised so the caps closed the air gaps and created a seal, with a weight on top to hold them down (just like they will be in most applications in your home) I would like to see this redone and rather than an airhorn use a free for use song so you can get the decible readings and see how it muffles actual spoken word) The reality is you still want to hear the fire alarm, you dont want to hear the in house theater though.

@@doomsdayscouts It's actually better to use a constant noise as the sound pressure meter can give a much more stable and accurate reading. With music the level would be bouncing up and down so much it would be hard to see what the actual level was, and even harder to see what the real difference in level was between MLV and open air noise readings. Higher frequencies aren't that difficult to stop though. I'd like to see this stuff tested to actual frequencies. Particularly low frequencies. I suspect the fall off in effectiveness would become drastic the lower the frequency. Not trying to diss the product, I intend to use it myself, but would appreciate some actual efficiency results at varying frequencies to be armed with the expectations of how well it will perform for my specific needs before buying it.

Yes but you might be better with the specific sound proofing underlay that combines MLV with closed cell foam

Ideally you'd need to decouple the walls and floors

I agree; I think the heavier box also insulates the bottom better and skews the final result. There should be some putty seal at the bottom.

2lbs MLV goes from 92Db to 70Db that’s pretty damn good

Sound transmission by air waves and sound transmission by vibration are 2 entirely different things.

You’re better off building a platform or not drop the weights?

Short answer is not really, to negate the thump you basically need your floor to be decoupled from the ceiling below it. It would be a lot more expensive than simply laying some MLV

I don't even expect that at 1 KHz honestly. MLV is great for something like padding a carpet, but it's not gonna magically block out sound from neighbours if the construction is already bad. But people hype it like it'll fix all your problems when really what you need is a decoupled nearly air tight environment. Which won't happen in buildings with shared walls. It's your wall, whatever insulation they're legally required to put, then the neighbour's wall, despite the fact that renting will cost the same as a house over time (2 bedroom apartment where I live is $1600/mo, over 20 years that's $384K which would get a decent sized house here).

MLV is installed like a limp mass. imagine it like a huge heavy curtain in void between walls.

@@D22D21 Right, and builders know this, but the average person watching this is going to think they can just staple it to their existing walls and think it'll magically stop the low frequency noise that's traveling through the structure when really it should be in the walls and under the floorboards already. I used carpet padding as an example because I think that's a place where it you can place it onto an existing structure and actually see an improvement in the reduction of regular footfall noise. For homeowners they can install the MLV during renovations or on the wall and place additional drywall, but the people renting apartments probably can't do that. And a lot of people who watch videos like these are living in rentals and trying to find a way to deal with noisy neighbours. But a lot of MLV products are marketed like it's magic bullet that will silence neighbours and even have testimonials to support that whether or not it's accurate. The really bad offenders for noise bleed like the 500 Hz region and below aren't going to see the reduction in the video as you said, and however much actually does get reduced won't be as noticeable as people are hoping. If I were building a vocal booth with layered walls I would absolutely install MLV in it, but I doubt people looking up how to soundproof on KZfaq and watching stuff like this with the intention of building/renovating their place

And there are acoustic blankets and stuff like the VocalBoothtoGo soundproof booths that use MLV and advertise similar sound dampening like the 20 dB we see in the video but that's only on the high end and is just placed on existing walls, so really they're absorbers for reflections that are being sold like they're blocking low end sound. I've seen such products advertising 25+ dB reduction AND more on the high end giving the impression that the low end and low mids are getting a 25 dB reduction which would be amazing if it were actually possible.

​@@dylanj8676 I think you are right, i have also made research what i could use for blocking noise in my apartment coming from downstairs apartment. It is not very big problem, i can hear their TV and loud talks slightly but still disturb me at nights. Since i decided to make other renovations, i also plan to lay thick layer of MLV (5cm - 2") under my laminate flooring. I am just not sure if that would make a any difference, but whatever it will be, i will give it a try.

It does not. I don't think anybody who recommends that as any experience with recording. They're solid so they don't absorb, and they're symmetrical so they don't diffuse. They do help with one specific spot, but the broadband reduction is so bad it's essentially useless and also a huge fire hazard. If you want cheap sound deadening you use moving blankets. They work better than most acoustic foam, but not as well as mineral wool or rigid fiberglass, which actually might be the cheapest option relative to performance and is what any studio I'd call legitimately professional would be using.

No that is sound absorption not sound deadening

And then came the horn, I am british so I find all this hilarious.

I’ve got you covered: “BRAAAAAAAAAAAAAAAAAAAAAAAAAAA”