SoundProofing

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I've moved this to https://we.riseup.net/yummyben/soundproofing-notes for any future editting.

Before the first event held at the rampART we know we had to do something improve the sound proofing of the hall. Many of the windows were smashed and it would be almost as loud outside as in. Knowing nothing about sound proofing we used the materials to hand - vast quantities of flattened corrugated cardboard boxes thrown out by the clothes wholesalers on commerical road. Our efforts did help reduce the noise although this may have been more to do with covering up the holed windows rather than some magical property of eight inches of cardboard.

Several months went by with no known complaints about noise but the cardboard was a blatantly a major fire risk so when we finally did get slapped with a noise abatement order we decided to redo the whole thing properly. We did some reading and then starting collecting bricks from skips, and buying bags of sand plus cement. Teaching ourselves the basics of brick laying we then proceeded to brick up all of the ground floor windows. The only one we didn't brick up completely was the kitchen window where we added another window inside the frame to provide double glazing. The results were amazing. Only the heaviest bass sounds made it out to the street. Job done.

Unfortunately we had done such a good job that even air was unable to get in or out of the hall and during events it become unbearably stuffy with condensation dripping off the ceiling. The only solution was to fit a ventilation fan in the outside wall which reduced the efficiency of the sound proofing by a surprising amount. We still generated complaints but invariably they related to noisy behaviour of people spilling out into the street rather than music from the venue.

Everything changed when a year or so later we constructed a fire exit from the hall out into the back street. The new door seemed impossible to adequately sound proof while retaining their function as an emergency exit. With much high levels of sound escaping the building we decided to end all events at midnight at the latest instead of at two. Even so, it wasn't long after that till we got our second noise abatement order. We never did solve the issue of how to sound proof the door, instead we ended up boarding it up (with a sandwich of concrete soaked carpet, wood, metal and a mattress) but that's a different story.

Sound Proofing Materials

Soundproofing can be achieved by either absorbing sound energy or reflecting it. A good soundproofing material will have on of two key properties - one is mass so the air pressure waves can't cause the material to vibrate and the second one is "soggyness" so that the energy of the sound waves is 'absorbed' (transformed into thermal energy). To absorb the sound, the material must distort and the internal friction dissipates the sound energy as it moves. High frequency sounds can easily be dealt with by absorption but it is much hard to deal with low frequencies in the same way.

You'd need a massive depth of material to have any impact on low frequency sounds which has wavelengths measured in metres rather than cm's. It is possible to design structures which resonate at a specific frequency and have damping mechanisms inside (bass traps) but it's not really a practical proposition. The most practical way of dealing with low frequency sounds is to reflect them. This requires material as massive (dense) as possible, so that it won't vibrate in the first place. It's normal to use as much mass as you can afford. Lead is really good but very expensive. Concrete blocks are good, brick also. Light weight breeze blocks are not so good but easy to get and work with, they are way better than nothing.

Materials that make good thermal insulation are not necessarily any good for sound proofing. Styrofoam and expanded polystyrene foam for example are actually really good conductors of sound so don't try to use them for soundproofing.

A common myth is that a wall covered in egg boxes will somehow improve your sound proofing - that's total crap. The misconception comes from the fact that egg boxes look a little like the shaped acoustic foam used in sound studios as part of their efforts to shape sound, reduce reflections, break up standing waves etc. None of that has anything to do with sound proofing and egg boxes will contribute absolutely nothing so don't waste our time.

Windows are the biggest problem. There are several methods to reduce sound passing through a window, depending on whether you need light or not. Replace the window with vinyl framed double or triple glazing or add another window on the inside of your existing window. If you don't need the light, place a sound barrier in the window frame. Are you busy as a bee? Do not even have time for fun? Do your friends advise you to buy essay writing example? Do not hesitate! Come after the advice of clever men and make a correct choice! Ideally brick it up but you could use old mattresses and rags with a board over it.

Doors are also a pain but at least you are likely to have less of them to deal with. They should close fitting all round with rubber draft proofing strips fitted. They should also be as thick and heavy as you can manage. It's a good idea to have a double set of doors (like an air lock) so that people have to open first one then the other to enter or exit. The more doors between your sound and the street the better.

Holes for cables and pipes can let through an incredible amount of sound seal them with with mastic or filler.

One area of misunderstanding with sound proofing is the role of cavities. Dead air space works for you better than filling it up with something! Packing stuff in to cavities can make the sound transfer worse! Larger air gaps Are superior to several smaller ones. This means a stud wall with 6" air space is better than may be better than a 4" stud way with an extra layer of drywall with 1" air spacing on each side.

Making a sound wave transfer through different layers of material with different densities assists in noise damping.

Most transfer from a room to the outside occurs through mechanical means. The vibration passes directly through the walls, woodwork and other solid structural elements. When it meets with an efficient sound board such as a wall, ceiling, floor or window, the vibration is amplified and heard in the second space. A mechanical transmission is much faster, more efficient and may be more readily amplified than an airborne transmission of the same initial strength.

The use of acoustic foams and other absorbent means are useless against this transmitted vibration. The user is required to break the connection between the room that contains the noise source and the outside world. This is called acoustic de-coupling. Ideal de-coupling involves eliminating vibration transfer in both solid materials and in the air.

A Room Within A Room is one method of isolating sound and stopping it from transmitting to the outside world where it may be undesirable. This is how sound studios are made but unlikely to be practical for a gig space. However, 'false walls' are a pracical proposition. Plasterboard stub walls built so that they don't actually touch the orginal wall and with a decent size gap between them.