Sound-muffling fencing?

Discussion in 'GEAR Talk Forum' started by chillbot, Mar 17, 2019.

  1. chillbot

    chillbot Sock Muppet

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    If you had a studio, and you had a neighbor, and your neighbor had kids that you didn't want to hear, and you didn't want your neighbor complaining about your music studio, what kind of fencing would you put in? Any thoughts?
     
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  2. OP
    OP
    chillbot

    chillbot Sock Muppet

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    Capture.PNG


    There is roughly 50 feet between main studio windows and said fence.

    There's also a row of tall mediterranean cypress trees between which helps.

    That pool just got filled in.
     
  3. studiostuff

    studiostuff Active Member

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  4. wst3

    wst3 my office these days

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    I wouldn't put in fencing at all. No fence can provide much in the way of acoustic isolation. There is only one way to block sound transmission, and that is mass, the more mass the more isolation. OK, there are additional requirements, like air tight, but mass is still the key.

    You could build a solid wall (sound familiar???) of concrete or sand filled block and that would provide some attenuation, but there are so many flanking paths I fear it would still be inadequate.

    Distance is your other friend, and 50 feet will provide significant isolation, but probably not nearly enough.

    While not cheap, I would build out the walls to provide additional isolation. It does not have to be as difficult as some suggest. And it starts with an analysis of the current studio to find the weak spots.

    Sorry, that probably doesn't line up well with what you would like to do.
     
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  5. OP
    OP
    chillbot

    chillbot Sock Muppet

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    Nope.

    So let's say one fence would reduce sound by 1.5% and another fence would reduce sound by 3.5% I want the 3.5% one, that's all I'm asking. The fence is going in either way. Notice I said "sound-muffling" not "sound-proofing".

    We are not very loud to begin with, but when the windows are open I'm hoping to stop a few of the high frequency directional sounds that are aimed in that direction.
     
  6. wst3

    wst3 my office these days

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    Chill old buddy old pal - I hope I can still say that in a minute or two...

    The reduction you are talking about is insignificant. even a 5% reduction amounts to less the 0.5 dB.

    But hey, I'm not there, so maybe I am wrong? Happens a lot.

    A little background, if you already know all of this please ignore, I mean no disrespect!

    A "typical" human experiences a 10 dB change as half (or twice) as loud.
    That same "typical" human can perceive a 1dB change if they are working at it, but probably requires closer to a 3dB change to make it noticable.

    We are NOT talking about you - your ears are most likely much more alert.

    Similarly, we talk about 3dB as a doubling of power (e.g. sound power, electrical power) and a 6 dB difference as a doubling (or halving) of intensity (e.g. sound pressure, voltage). The reason for the difference is left for another time.

    Also note that in free space (and your yard likely qualifies) sound is attenuated by distance according to the good old inverse square law (same as gravity, coincidence? I think not).

    Put more simply, you will reduce the sound level by 6 dB every time you double the distance from the source. If the SPL is 85 dB at 1 meter it will be 82 dB at 2 meters, 79 dB at 4 meters, and so on.

    It is important to note that isolation and/or attenuation generally works equally in both directions. Your music will be attenuated at the fence by the same factor as the kids noise is attenuated at your studio.

    May I assume you have a smart phone? Doesn't matter iOS or Android, get yourself an inexpensive or even free SPL meter for your phone.

    Play pink noise (or music, we're not going to court) at roughly the level at which you like to work. Now add 3 dB just for grins.

    Go stand directly outside your studio, preferably at a window or door, and measure the sound pressure level. A-Weighting is fine for this sort of thing.

    Now walk about 10 paces (good thing the pool is filled in) and make the same measurement.

    Finally make the same measurement at roughly where the fence will go.

    Send me those numbers and we can have a more productive conversation.

    And again, if you know all this already I apologize!
     
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  7. Gerhard Westphalen

    Gerhard Westphalen Scoring Mixer

    I'd suggest looking into those barriers that separate busy roads from residential areas. If you've ever stood next to one, they're pretty effective compared to having nothing. The only issue is that the farther you get from them, the more that sounds bends around them so 50' might be too far for a reasonably tall barrier to make a difference.

    IMO your best bet would be work on isolating your studio. Start with doors, windows, and HVAC and if that's not enough then consider changing the walls, floor, and ceiling. Considering the distance that you have to your neighbors, getting your room properly sealed will probably be enough.
     
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  8. OP
    OP
    chillbot

    chillbot Sock Muppet

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    I'm not doing all that.

    I'll put you down for "concrete or sand filled block" thanks.
     
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  9. studiostuff

    studiostuff Active Member

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    Is it at all possible to negotiate for peace with your neighbor...?

    (Yes. I'm an aging hippy...)
     
  10. OP
    OP
    chillbot

    chillbot Sock Muppet

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    When we built the studio I filled the walls with Auralex sheetblok in between two layers of drywall. It's quite enough for what I do, the biggest weakness is the windows but it's still barely audible outside at normal volume levels.

    Maybe I'm not making this very clear sorry. I'm not trying to use a fence to replace proper sound reduction. But when the weather permits I like to have the windows open for fresh air. (If I'm going to mix something loud I shut the windows.) There is almost a direct line from one pair of speakers:

    Speakers ---> 15 ft ---> Window ---> 50 ft ---> Fence ---> Neighbor. It's a straight line, I'm not worried about the low frequencies, I'm thinking about the directional audio waves that are going straight out the window into the fence.

    The fence is being replaced. My question is simply is there a certain kind of fence I should consider?

    I'm thinking the taller the better (plus tall = more mass). It could be a double-fence with wood on each side of cinderblocks for mass?
     
  11. OP
    OP
    chillbot

    chillbot Sock Muppet

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    Never had a problem, never gotten any complaints from any neighbors in 5 years we've been here. This is just about, the fence is getting replaced ANYWAY so why not try to make it the best possible fence to keep the complaint rate at zero.
     
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  12. DavidY

    DavidY Active Member

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    I was going to suggest that too. There's a road near me which has them and the fence panels are stuffed with something which looks like sheep's wool.
    That said, the fact that I have some idea what they're stuffed with says something about the longevity of the panels, although that could be vandalism which may not be an issue for you.
     
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  13. Gerhard Westphalen

    Gerhard Westphalen Scoring Mixer

    Yes, the taller, the more distance you have before the sound bends down and hits your house or neighbors. At that distance, I'm not sure how tall that would be. It could be that a 20' wall would be completely useless. I'd try finding some examples of the road barriers and see their height vs distance to the road and houses on the other side. I don't think a standard wooden fence height would work. You'd need more of a real wall that people use to stop intruders. If kids are playing right beside the fence then you only really need to be taller than they are.

    That would probably work very well if it's the right height.
     
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  14. PaulBrimstone

    PaulBrimstone Far, Far Away

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  15. wst3

    wst3 my office these days

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    So yeah, you might have buried the lead a little<G>...

    It sounds like you covered most of the bases when you built. Loaded vinyl is one of the best forms of isolation available - limp and massive.

    I know you don't really want to make those measurements, so I will estimate.

    Mix level at your ears (guestimate 1M) is around 85 dB-SPL
    Level at the window is (call it 4M for simplicity and derating) will be about 73 dB-SPL
    Level at the fence will be roughly 50 dB-SPL.

    Putting that into perspective we assume that normal human conversation is around 60 dB-SPL.
    We recommend the background noise in a conference room or classroom to be no more than 40 dB-SPL (20 dB S/N ratio is considered the minimum for good speech intelligibility - doesn't really apply here, but it gives an idea of scale.)

    So think of a noisy classroom or conference room and that's going to be in the ballpark of the sound pressure level at the fence, based on the assumptions above.

    Is that enough? Would an additional fraction of a dB make a difference? I can't answer the first, but I can't imagine that the second is true.

    So you will need a tall, wide wall (this is no longer a fence<G>). How tall and how wide are probably best left to someone with eons of experience in this sort of thing because none of the references I found this afternoon made much sense, as in they would be ridiculously expensive, and probably violate some ordinance or another. As a SWAG I'd suggest about 10 feet high and the entire length of that property line. There will still be a significant flanking path, but that's just physics.

    Construction? I'd find someway to build with two dissimilar layers (block and wood?) with an air gap between - not unlike a studio wall. Avoid the temptation to have an air gap on either side of the block, it will reduce the isolation.

    If you don't think you need quite that much isolation then just go with a solid wood fence/wall 10 feet high running the entire length of the property line. I think that would provide another 3 dB or a little less) of attenuation, and since you aren't looking for all that much it might be sufficient.

    If it isn't you still have the option to add layers.

    Hope thaht's a little more helpful.
     
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  16. givemenoughrope

    givemenoughrope Senior Member

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    You know those plastic rocks they have at the Grove and Americana, the ones they play Sinatra-esque (but not Sinatra) garbage out of...? Install like 50 of those and just play the sound of wind, chipmunks, birds, cars and trucks passing. The key is distraction.
     
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  17. OP
    OP
    chillbot

    chillbot Sock Muppet

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    I have some money, yes.

    Maybe not quite enough.

    Also:

    "PLEASE NOTE: AIL Sound Walls are site-engineered solutions and generally aren’t suitable for smaller residential projects."

    Looks like the right idea though, maybe I could build something similar out of rockwool and ... ?
     
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  18. gregh

    gregh Senior Member

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    http://www.privacyblockfencing.com.au/services/ might work and be available in your area. We looked at this recently as a neighbour just installed the world's loudest pool filter with no sound insulation around it - butts up to the flimsy fence and is way above the permitted council noise levels. Except the council refuse to enforce the regulations - which is quite typical for regulatory bodies in Australia. Anyways decided to improve the sound insulation for my studio in the house rather than try this wall in the garden. Still might do the wall later
     
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  19. studiostuff

    studiostuff Active Member

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    I misunderstood your OP... Always a good plan to do what you can to keep everyone happy.
     
  20. Mike Greene

    Mike Greene Administrator

    I don't know what the best option is, but here are a few random thoughts:

    Even a Donald Trump approved concrete wall 20 feet high isn't going to stop all, or maybe not even most of the sound, so I'd be careful about spending too much money, since the results might be really disappointing. I sampled the piano in my house last summer and had to stop a zillion takes because I could hear the kids next door playing in the pool, which is across the other side of my house, about a hundred feet away, over a slight hill, and on the other side of a fence that's more than high enough to visually (but obviously not sonically) block any action there. Obviously you're not going for "sampling level" quietness, but I was surprised how much sound carries around obstacles.

    A concrete block wall 6' high or more is going to require a legit footing, probably 2 or 3 feet deep and 2 feet wide, with a bunch of rebar in there. It might also need a permit if it's over 3 feet high. (If you do it without a permit, you could run into liability problems if the wall falls on someone in an earthquake.) Concrete block is pretty ugly, so you'd also need to add something nice looking on both sides. My guess is that all in, going this route will cost at least low five figures.

    My feeling is that for sound isolation, the higher the fence, the better, since sound doesn't travel strictly linearly. But if it's over 6 feet high, you have to get permission from the neighbor. (At least in L.A.) That might be tricky, not just from the neighbor, but from your wife and even you when you start visualizing what a high fence would actually look like. A high fence screams, "There's something bad on the other side of this!" :grin: 12 feet high would be great for blocking more sound, but there's a visual cost to that.

    I could be wrong, and Bill knows far more than I do, but I've always been under the impression that bass doesn't travel well, so I don't think you have to get too heavy duty with this. Mids and highs get blocked (with the caveat that sound doesn't travel linearly) without too much bulk.

    I'd do a wood fence, maybe 8 foot, but my concern is that with typical wood fencing, there's always a space between the boards/planks. That's really bad in this situation, so I'd be tempted to cover both sides of the framework, for double the coverage. Gaps between the planks might still be an issue, though. I really don't know. What I do know, though, is that contractors often advise against covering both sides because then spiders will make their homes in that dark area in between. (Hey, I did say these were random thoughts!)
     

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