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TOPIC: sound proofing

sound proofing 09 Jun 2003 21:59 #28280

  • crshedd
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i have been told how to build a sound proof wall between screens but how do you sound proof the ceiling if you have an apartment above (or below for that matter?

thanx

ps-assume building from the ground (or basement) up. thanx.

'hey! there's no party here!'
jeff spicoli
fast times at ridgemont high

[This message has been edited by crshedd (edited June 10, 2003).]
'hey! there's no party here!'
jeff spicoli
fast times at ridgemont high
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Re: sound proofing 10 Jun 2003 13:15 #28281

  • jimor
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Soundproofing is a sub-study of acoustics, and there are books in any large library on that subject. If you are talking about retrofiting an existing building's ceiling to prevent sound from entering another space, you are talking mass to absorb sound energy. Many people confuse the dynamics of REFLECTED sound with those of TRANSMITTED sound. Acoustic tiles and draperies have been used for years inside auditoriums to stop unwanted Reflected sound, but to stop the energy of sound from piercing barriers one must not only stop up any holes, but also calculate the mass of the intervening barrier as to its ability to absorb sound, since even a Reflective surface always allows some sound to pass through. Acoustics textbooks have charts of 'constants' of sound absorbtion ability of various thicknesses of verious materials in different constructions; consult these to get a better idea of soundproofing ability.

Ever been in a multiplex with concrete block walls between the screens and STILL have been able to hear the program in the other auditorium? I'm sure most of us have. That well demonstrates that even relatively heavy concrete block (in a single layer) is not sufficient mass to absorb the energy of multi-hundred watt sound systems with many speakers. The best such divider walls are of poured concrete or at least of heavy brick, since these materials, if properly installed and not pierced for anything more than electricals, are of sufficient mass to absorb much more energy than concrete block or lesser materials such as wood or plaster.

Since mass equals weight, the successful materials will require a superstructure capable of supporting such added weight. The old movie palaces had extra heavy steel capable of supporting concrete slab roof decks that adequately kept air-borne sound from penetrating the auditorium. The cost of such construction today is prohibitive, and in your retrofit situation, only cast concrete panels or pyrobar slabs would provide the isolation of sound that you seek, but will your existing structure support them? I doubt it. In any case, if you are serious, you should consult acoustical and structural engineers to get competent estimates. Beware of any building contractor who will assure you that their approach is cheap and effective, for you will be stung after spending thousands to find that peaks of noise will still awaken your tenants upstairs.

If you are willing to remodel the apartments by removing finish flooring (and cabinets and bottoms of walls and doors!) and laying down a layer of bricks, grouted in place, you might achieve an acceptable level of sound proofing, but you MUST have a structural engineer prepare plans and have him certify in writing that they meet local codes and will not over stress your building's structure. The bed of sand usually needed under bricks will also serve to stop sound through its mass, but will also add weight to the sturcture, which increases the hazard. This is not an area to experiment with!

If multiple layers of acoustic tiles can be safely mounted to the ceiling below and the degree of sound proofing is acceptable, you might experiment to that extent, but still be very careful of the total weight -- including any rigging/hardware -- that is installed. I know of a small auditorium where acoustic tile panels were screwed to an existing plaster ceiling to improve acoustics by reducing reflection, but one night it all came down, destroying a number of the joists with it. No one was hurt, but the embarrassment as well as repair bill was high! No expert was consulted as to what the structure or the screws could bear. The city found out about the non-permit alteration, and then fined the owner, as well as strictly supervising the subsequent repairs to the letter of the law.

Your goal is noble, but buildings have collapsed in the past due to miscalculations in adding such weight. Perhaps it would be more cost effective to change the occupancy to offices or the like that will not be occupied at night or on weekends during your shows. Best Wishes on a difficult situation.
Jim Rankin, member www.HistoricTheatres.org

[This message has been edited by jimor (edited June 10, 2003).]
Jim R. (new E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it ) member: www.HistoricTheatres.org
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Re: sound proofing 11 Jun 2003 13:37 #28282

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Mike, have you gone in to one of those vacant rooms above your theatre in Houlton? If so, how do they sound?
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Re: sound proofing 13 Jun 2003 13:04 #28283

I have seen theatres in parking garages use an acoustical tile ceiling with an addition cut out of sheet rock placed over each acoustical tile for sound. You would need to make sure your current drop ceiling is supported enough to hold the extra weight. Have also seen in a two story theatre were THX made them hang 4X8 sheet rock by wire between the floor above and the drop ceiling creating an additional ceiling for sound proofing.

[This message has been edited by Greg Pauley (edited June 13, 2003).]
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Re: sound proofing 13 Jun 2003 13:40 #28284

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There's absolutely no sound upstairs over our theatres. There's heavy layers of acousitical plaster. Also: it was built to hold whole band concerts, etc. so there's a big thick preventitve medicine dose that was done back then.

We built a seperate standing wall between our front two theatres when we added a 3rd behind them. State=red with a full 2/6 stud wall, with fiberglass insul, 2 layers of thick sheet rock. We wree playing Twister at the time... good test film!
and we added a new layer of tile rock material over spacers and one more sheet rock. That did it. Inside our booth we used vibe dampening straps, alternate layers of rock, separated stud walls, and a booth floor that floats on big sound and vibe absorbers: no part of the booth floor is attached to wall or sub floor.



Michael Hurley
Impresario
Michael Hurley
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Re: sound proofing 13 Jun 2003 20:29 #28285

  • crshedd
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some great input that even i understand!
thanx for the responses and keep 'em coming!

'hey! there's no party here!'
jeff spicoli
fast times at ridgemont high
'hey! there's no party here!'
jeff spicoli
fast times at ridgemont high
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