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Topic Title: soundproofing and cables and decibels
Topic Summary: Questions about those two
Created On: 20 March 2015 08:39 PM
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 20 March 2015 08:39 PM
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Zs

Posts: 3814
Joined: 20 July 2006

hello,

The shed which is going to give all you shed-dwellers that thing that they refer to as shed-envy is under construction.

Wow it looks so big now that the frame is up. 4m x 3m and it is going to be perfect. The intended purpose is office, technical book collection and somewhere to be able to play the guitar(s) without having to use headphones. I'm not a very good player and I prefer to hide my inadequacy from my neighbours. I also rather fancy a Roland drum machine, but only for laying down backing tracks for myself. Not like Animal off the Muppets or anything.

First the Soundproofing and cables issue. It is timber. From the outside; a layer of cedar overlapped planks on three sides which they refer to as 'feather edge', the front will be logs. then a 4 x 2 timber frame with a vapour membrane (? don't really know what that is but I trust them), in the timber frame a layer of something acoustic which looks to be quite compact and not just like our usual Isover/rockwool, then a layer of soundboard instead of plasterboard. At that point they will leave it to me and I think it will have a cushioned layer with a fabric cover which is probably going to cost me more than the rest of it. That last bit with the cushioned layer is so that if I ever record it doesn't sound echo-ey. The roof is 5 x 4 timbers and I think and it will get two layers of the firm insulation in it. The floor will be ply on top of a thick layer of cellotex/kingspan and then over to me. One tiny window and probably glass in the top half of the double door. No other windows, for security reasons.

So...

Do you know of any reason or anything about serious firm insulation in the walls which has an effect, other than our usuals, on current carrying capacity etc.? I'm taking advice but I just get blank looks. It looks to me as if it is the same. There's going to be a dado rail trunking and loads of sockets but usually it will only get office use or a small guitar amp. Some heating though. I think lamps not light fittings and nothing close to the fabric walls but I've not decided. I reckon max 20A poss 30A while it warms up on a freezing cold day. I'm looking for a ten-minute warm up.

I so don't want this to catch fire. I can't find anything to tell me that it will but please let me know if you have any horror stories or advice. I'd like this to be right first time.

Crazy, it's a shed but I already love it so much.

Then, this might sound a bit silly but could anyone tell me what decibels sound like? For example, what kind of thing makes a noise that is 82 decibels? What makes 100 and so on. I can find loads of information on the web about how much sound leaks out through glass, soundboard, rockwool etc. but they all forget to tell you what the levels mean.

I'll be in the shed...

Zs
 20 March 2015 08:59 PM
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rocknroll

Posts: 9540
Joined: 03 October 2005

Then, this might sound a bit silly but could anyone tell me what decibels sound like? For example, what kind of thing makes a noise that is 82 decibels? What makes 100 and so on.


You need to look up, Marshall Chasin , M.Sc., Aud(C), FAAA, Centre for Human Performance & Health, Ontario, Canada, he has done a lot of papers and charts in this area, and you should be investing in some vented earplugs by now also.

The cheapest option is 12" x 12" (300mm x 300mm) egg trays, the recycled cardboard type and stick them all over the walls and ceiling as you would any tile, that avoids reflections and reverberations and is a very good soundproofer.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------

Edited: 20 March 2015 at 09:09 PM by rocknroll
 20 March 2015 09:11 PM
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sparkingchip

Posts: 9953
Joined: 18 January 2003

I was doing a job for a District Judge who lives under a airport approach path, he had a Ordnance Survey map spread out on a table carefully marking predicted sound levels in decibels after proposed changes at the airport.

I passed comment that he needed to remember it it a logarithmic scale, then outlined what this means.

The judges response was "The !@#$@/^* didn't tell me that"!

Andy
 20 March 2015 09:16 PM
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John Peckham

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Zs

Have a look at the HSE web site on noise. Noise is a bit like ionising radiation in that the level and length of time exposed will determine the amount of permanent damage to your body. As someone who has permanent hearing damage from things going bang next to my ears I am very careful now, horse, door, stable bolt a bit late. Your employer may have a sound pressure meter you can borrow to measure your exposure.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 20 March 2015 09:31 PM
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Fm

Posts: 1710
Joined: 24 August 2011

Have a look at the british gypsum website

You want to add some density to the walls
Soundblock plasterboard with staggered joins, double sheeted both layers taped will help considerably
 20 March 2015 09:44 PM
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davezawadi

Posts: 3843
Joined: 26 June 2002

Hi Zs

Right what does 100dB sound like? It is the level of the loudest concert you have experienced, with the possible exception of Metallica who might have ignored the rules. The peak level will have been a little bit more, but the average (A weighted but you can ignore that) will have been 96dB, which is fairly safe for two hours, and is the licence level for venues.

90dB will sound to you as about a quarter as loud, so a loudish record player.

80dB is about a quarter as loud again, probably like you listen to the TV.

Just to give you an idea, a big PA system at 1 metre distance is about 140dB, and will give you instant hearing loss, so don't try it!

A quiet day in the country is about 45dB from the birds and wind.

Now you can get 20 - 25dB reduction with your shed walls and mostly no gaps or air holes. A further 20dB is available if you line it entirely with 100mm of rockwook slabs (preferably the high density acoustic kind, but roof insulation is OK at mid (guitar) frequencies. If you play the bass or drum kit the heavier acoustic type is necessary.

Your guitar amplifier of 50W will give about 125dB at 1m when clipping (approx number, several variables) so 45dB from the shed gives about 80dB at 1m, worst case. Not too bad, a residential generator runs to about 75dB, so the neighbours are unlikely to complain.

Send me a PM for more gen, or even to borrow a sound level meter. More help if you need it. The phone number is on my website.

Regards
David

-------------------------
David
BSc CEng MIET
david@ZawadiSoundAndLighting.co.uk

Edited: 20 March 2015 at 09:51 PM by davezawadi
 20 March 2015 09:45 PM
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sparkingchip

Posts: 9953
Joined: 18 January 2003

Top of the range had phones will be cheaper.

Though it will be warm in winter and cool in the summer, is it getting a single room heat recovery fan? If so the duct will need attention regards reducing sound transmission as well.

Andy
 20 March 2015 09:48 PM
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davezawadi

Posts: 3843
Joined: 26 June 2002

Playing with headphones is a disaster sparkingchip, nothing like the real thing!

-------------------------
David
BSc CEng MIET
david@ZawadiSoundAndLighting.co.uk
 20 March 2015 09:49 PM
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Fm

Posts: 1710
Joined: 24 August 2011

im doing my vw camper van with sound deading material to kill the engine bay noise.

Have a look at the noise killer website
 20 March 2015 10:10 PM
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stateit

Posts: 2668
Joined: 15 April 2005

Originally posted by: rocknroll

The cheapest option is 12" x 12" (300mm x 300mm) egg trays, the recycled cardboard type and stick them all over the walls and ceiling as you would any tile, that avoids reflections and reverberations and is a very good soundproofer.


From my neighbour's experience (full-time musician) egg boxes deadens the acoustic response in the room - (giving a flat acoustic) but doesn't really stop the sound getting out of the room...

[edit] And my favourite place for playing guitar is my vaulted ceiling extension with hard (sound) reflective wooden floor and plastered walls. As it sounds the best when playing. For best aural effect I wouldn't want to listen to myself play in a carpeted and egg-boxed room.

The benefits of that are when recording and then doing any EQ/effects post-production. Which may not be Zs's wont.

In which case very dense walls are the option. [/edit]

-------------------------
S George
http://www.sg-electrical.com
 20 March 2015 10:18 PM
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sparkingchip

Posts: 9953
Joined: 18 January 2003

My loudest music experience was Saturday 25th August 1979.

One of my brothers is a music booking agent and he booked The Scorpions into the Reading Festival as Thin Lizzy could not make it.

We went to Reading in my less than trusty Simca van with my sister in law in the passenger seat and my brother in the back with the smoke machine cylinders, as you do.

As we were back stage we walked under the stage to stand in the pit in front of crowd security looking up at the stage with The Scorpions performing having the drummer on a revolving hydraulic drum riser.

This did mean we were stood between the speaker stacks and as we did not have any hearing protection we did actually cut the experience short to beat a retreat to the back stage bar The Ligger Inn.

Andy
 20 March 2015 10:36 PM
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Paradigm

Posts: 853
Joined: 10 September 2010

Zs

My loudest experience was Motorhead, Hammersmith Odeon on the Ace of Spades tour in the early eighties and I believe it was this gig that gave me the tinnitus that I have today.

as for the soundproofing, I have a very good friend who has a custom built soundproof studio in their back garden, they work as a dj, remixing a lot of stuff thats played on the radio and if you want any information, I could ask him to let me know how it was accomplished. Send me a mail.

Hope you are well, I have a new toy to show you at some point, got it at Hobgoblin Music for my birthday.

Nick

-------------------------
"be careful of what you write"
 20 March 2015 10:44 PM
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Fm

Posts: 1710
Joined: 24 August 2011

Google interstatial condensation
Vapour barrier on the inside ie warmside effectively a sheet of plastic. To stop damp warm air passing into the building fabric
 20 March 2015 11:34 PM
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stateit

Posts: 2668
Joined: 15 April 2005

Originally posted by: Zs... No other windows, for security reasons...


You should move to a respectable neighbourhood Zs . You can have windows

[edit] Having typed the above sentence, I checked my postcode for reported crimes... 50 reported last year in a mile radius. It's on the up.

Versus 26,052 reported crimes last year within a mile of my brother's postcode in E1... [/edit]

-------------------------
S George
http://www.sg-electrical.com
 21 March 2015 12:26 AM
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mapj1

Posts: 9346
Joined: 22 July 2004

DEcibels are just a ratio of two powers. Adding 10dB is multiplying by 10, subtracting 10dB is dividing the power by ten.

If you think money is power then a pound is a penny plus 20dB.
Sound tends to be in dBA - 0dBA is about the threshold of human hearing in perfect silence at standard distance (hearing a pin drop at 1m perhaps)
+30dBa is a quiet fan turning, or the bubbly thing in the fishtank.
+ 60dBa is office.
+80dBa is the small drill going. By 90dBa you should be wearing earplugs or similar if its more than short duration.
+120 is peak pressure during gunshot by your ear.

As regards the insulation, route the wire next to the external wood or against the internal surface rather than in the midst of it. It will be similar to rockwool - from the heat point of view the density doesn't matter so much, its still mostly trapped pockets of air that can't move very far or fast.
Or if you must , then do the lights in 1.5mm and the sockets in 4! or come up through the floor in trunk. if you need to drill though the membrane, tape up round the hole as much as poss afterwards - think as if it is a vertical damp course.

Ive seen some very nice anti- burglar window things made in the same way as a squirly wrought iron garden gate, and painted white they can look good and certainly stop folk getting in or out.


you will also see dB SPL (sound pressure level) based on an RMS pressure of 20micro pascals being 0dBSPL.

the conversion between dBa and dB spl is both level and frequency dependant, as our perception of equal volumes is not the same as equal pressures. But at 1000Hz its all the same


none the less, stay away from 100+dBs.
notes to frequency keyboard converison.

-------------------------
regards Mike


Edited: 21 March 2015 at 12:37 AM by mapj1
 21 March 2015 09:00 AM
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davezawadi

Posts: 3843
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Mike
Worrying about Fletcher Munsen curves at this point is not going to help Zs. Its a bit like giving a DI a bit of 1200mm SWA to joint. Its not the decibel that Zs is worried about, its the perception by the neighbours. We need to estimate the attenuation needed, the maximum level inside the shed and work from there. Obtaining 45-50dB overall at mid frequencies should be sufficient and is not too difficult. The problem has nothing to do with the internal acoustics of the shed, although they will end up very dead, but this is easily made more comfortable with a little electronics. Egg boxes on the walls will make no measurable difference outside.

-------------------------
David
BSc CEng MIET
david@ZawadiSoundAndLighting.co.uk
 21 March 2015 09:24 AM
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Zs

Posts: 3814
Joined: 20 July 2006

Mine was only last autumn; Beth Hart at the Royal Albert Hall. So uncomfortable that half the audience left. I think she must have thought she was doing a stadium. Painful. I'm not planning on making that much noise. Thank you so much for those, I've been looking some of them up for half an hour.

What level is singing?

I've learned that flush mounted sockets and accessories compromise the sound proofing massively so definitely a dado trunking. That takes away the cable capacity issue too apart from the incomer and I can bring that right in and box it (or push the desk over it). So that's good.

Ah, a smoke alarm in one of the pictures...I'd forgotten about that.

Then, the cushioned walls which I thought are soundproofing, aren't. I got that idea in my head from the walls in the music producer client's studio. They're actually absorbtion and reflectance. I guess they stop the village hall type sound and they're for recording. I reckon there's scope for making squishy panels. That can wait and could be a style thing when the time comes. Some of the pre made ones are over £300 a pop. I'm not at that level of expertise so I think I can use the DIY solutions. They debunk the egg box thing though.

Then the floor....oh. £££. In searching for max 60dB leakage I've found that I need to float a floor. I'm still on whether that's floating on an air gap or insulated. Good place for cables though. I could put a few in there. It's the office stuff that causes the mass of wiring requirements, not the music.

I suppose I should think about an earth rod for it too but we're all pme round here so I doubt it would make much difference.

It's a nice project though and about time to get stuck into something for myself. Kim the builder is on hols for 10 days so I can do infrastructure things while he is away.

Right, I'm off to Howdens to look at thick doors and triple glazing. I'll take the steep learning curve with me in my pocket with the Stanley fatmax tape.

Thank you. I really hope this works.

Edit, Nick, you get invited round to play of course. Big day for you on Tuesday... please can I tell?

Zs
 21 March 2015 09:57 AM
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impvan

Posts: 922
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A local welsh-language broadcast ecording studio near me relocated, and I got hold of their walls....

It's Fermacell, applied in 2 layers of 10 and 12.5mm. It's just like *very* heavy plasterboard, but the edges can be glued and if you're neat with the installation there's no need to pink it. An 8x4 sheet of the thinner one is around 30kg, I believe it's the sheer weight which kills the sound.

I retrimmed a lot of the boards and have used them in my own selfbuild. The sound attenuation is terrific. The biggest perceived noise source is what echoes down the chimney and out the woodburner.

I was so impressed with the (free!) recycled boards, that I bought new boards for the rest of the build when I ran out.
 21 March 2015 10:33 AM
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OMS

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I suspect you need to define two things:

1 - What sort of noise are you going to make in the box - and at what frequency - and how much can you allow to leak out

2 - What sort of response do you want in the box - ie how much attenuation at what frequency to give you the reverberation time you want/need

To get this into context, a fire alarm sounder is circa 96dBA at 1m distance - even a bog basic shed will clip that to circa 90dBA outside the building. From there knock of 6dBA every time you double the distance - so at 2 meters from the shed you'll be down to 84dBA - at 4m from the shed you;ll be down to 78dBA and at 8m from the shed you;ll be down to 72dBA - so a bit like putting the hoover on outside your neighbours window.

From all of that, you probably need to be thinking of getting the shed facade to work a bit harder than normal to get some attenuation in the region of 20dBA to allow for an increase in dBA at the house (by reflection off the wall - so add 3dBA)

So from outside in - cladding,( It will be even better if you can get a layer of insulation over the outer face of the studs before ading the cladding). reasonably dense insulation(packed rockwool or celotex between the studs) - then put 50mm of celotex over the studs and add at least one layer of soundblocker plasterboard - you are looking to control the "stiffness" of the shed panels. Then, over that, add counterbattens and add another layer of insulation up to half way and plasterboard over that. From the half up, stuff it with rockwool and add perforated hardboard panels (or even fancy rad cover panels) - you want to buid what is effectiely a helmholz resonator - so sound gets into holes and at typical frequencies based on the perforation diameter gets "stuck" in the rockwool and is lost as heat.

If you have the money, then add resilient bars to fix the PB to (or find a bit of 6mm EDPM rubber strap and use that - old wetsuits material is good)

From there, with a bit of basic measuring you now have a good idea of reverb time ie the time taken for a given sound power to decay to 1 millionth of the original value - so about 1 second for a space the size of a generous shed - to get to 1 second, add a bit of absorbtion material - dense upholstry foam is ideal. You could hang a " lighting raft" in the shed to carry the lighting and stick foam to the back of it (where it is effective but unseen)

Essentially the build up needs to be consistent - sound is sneaky stuff and find any "holes" in the structure.

If you have plenty of money and the room then just build a smaller shed inside the shed - that way you can decouple everything and use air gaps and stiffness contol - very effective, and not an unreasonable cost

It might be easier to think of what you are trying to achieve in terms of a sound reduction index - ie pick a construction that has a known Rw value - a typical fire door is about 25dBA from side to side.

Speak to the delicate one next week - she's pretty switched on to the physical construction to get to known RW values - it's how we typically address school design. I can lend you a few undergraduate texts if you want to do more on the physics side of things.

I'm seeing industrial chic - why don't you tube it out in surface galv conduit (avids breaching the construction lines) and then go for a bit of suspened galv tray in a random geometric and add absorption to the back and sink downlighters through the tray - that's your raft. Add a few industrial tubular heaters and away you go.

To get a bit of context, and going back to Rw values, if you achieve Rw 40 and given that you'll not be wanting sound levels much above 80dBA unless you are planning on going deaf very quickly, then (assuming 100mm stud) if you go cladding, counterbatten, wind proof membrane, 50mm celeotex, 100mm celotex between, 50mm celotex, vapour membrane, 18mm OSB (you could paint that and ditch the vapour membrane), counterbatten (or resilient bar but not cheap) and soundblocker board then you'll get 40dBA reduction. You can then add batten picture frames to the upper walls, stuff a bit of rockwool in there and add perforated panels (or even a reasonably open fabric in a couple of layers).

Put a good quality draught strip on the door (and any windows that open)

Good luck with it

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 21 March 2015 03:07 PM
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IronFreely

Posts: 322
Joined: 06 November 2014

With out picking on anyone's replies like a troll...
If you'd like to re-educate yourself regarding so called licence limits to sound levels for venues and events please follow the linkhttp://www.hse.gov.uk/event-safety/noise.htm
I'll just point out there is no "legal limit" to dB levels, just a duty of care. Casting my mind back to the last risk assessment - over 84dB ear protection must be available to employees, over 96dB employees must be physically reminded that ear protection is available and audiences must be warned by way of a sign or on ticket T's &C's if the risks of high levels of noise and distortion.
Remember it's distortion rather than volume that really damages the ears.

If you'd like to re-educate yourself regarding what a 10dB increase in sound levels actually feels like and literally is I suggest reading mapj1's near perfect explanation, give that man a reasonably priced cigar!

Zs, your shed sounds great, I hope it goes well. Some ideas for you... I have had succes in producing my own sound baffels by filling the reverse side of egg boxes with expanding foam to create that clasic studio wall look. Google searching DIY sound baffles and nouse reduction will come up hundreds of great ideas for home studio applications.
Finally for that last layer of echo reduction I suggest a material called "serge " it's that classic theatre black curtain, it's made of heavy wool and is considered inherently Fire proof for the first 10 years off the shelf (if will withstand a ten second match test, which is all you usually need in a theatre for a standard show risk assessment)
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