These are the references and definitions I found (check which one applies better to your context):


Geluid van de buren kan worden tegengehouden door een extra voorzetwand te gebruiken. Dat is een laag geluidsisolerend materiaal, bijvoorbeeld gipsblokken, op enige afstand van de bestaande wand. De tussenruimte wordt gevuld met absorptiematieraal (zoals steenwol). De extra wand mag niet aan de muur bevestigd worden, dat zou de geluidsisolatie sterk verslechteren. De exacte uitvoering van de constructie is erg belangrijk, en omdat het een ingrijpende maatregel is, is het verstandig om eerst een onafhankelijke geluidsadviseur in te schakelen voordat met het werk wordt begonnen. Deze adviseur dient ook te beoordelen of het geluid niet langs andere paden binnenkomt, bijvoorbeeld via het plafond of de vloer.
http://utopia.ision.nl/users/mier/faq_geluid.htm


... sound. By filling the cavity inside an isolation wall or ceiling with any low-density
material, the transmission of sound from one room s surface through a ...
www.foam-tech.com/B3c2.htm - 19k - In cache - Gelijkwaardige pagina's


[PDF] www.jm.com/Canada/products/commercial/CAN042_SoundShield.pd...
... the required the studs provide vibration isolation between the two wall surfaces.
amount of sound-absorbing material, and permits comparison Sound in one room ...
Text version - Gelijkwaardige pagina's



The challenge in designing effective soundproofing is to convert as much of the unwanted sound to heat as possible. The simplest way to attenuate sound is to put a solid wall in its way, and one of the fundamental rules that you should try to remember is that every time you double the mass of a wall you'll roughly halve the amount of sound transmitted. This means that to halve the sound leakage through an existing wall you'd have to double its thickness. AIR STUDIOS?
A soundproof room is an airtight room, so you need to think about how you'll get fresh air into the studio. Can you get by with opening the doors between takes, or will you have to install an air-conditioning system? Simple air conditioners just cool and recirculate the existing air, but a serious studio air conditioner that brings in fresh air from outside needs silencer baffles, large ducting, anti-vibration mountings and so on. This is likely to cost more than most complete home studios, so a compromise approach is most likely.


Another keystone of acoustic theory is that as the sound frequency is reduced, the isolation provided by a structure also falls. In fact, for every octave drop in pitch, the sound isolation is halved. From this, it's easy to see that soundproofing against high frequencies is not too much of a problem, but deep bass is very difficult to contain. You only have to walk past a nightclub to hear the amount of bass that can escape through solid brick walls!

Because attenuation is frequency-dependent, the effectiveness of a particular sound-absorbing partition design or material is generally measured in dBs, for a set of frequencies averaged over the range 100Hz to just over 3kHz. This figure is called the Sound Reduction Index, or SRI. A single brick wall might, for example, have a quoted SRI of 45dB, while a double-thickness wall made from the same material might be rated at around 51dB. This latter figure represents a lot of attenuation, but if you're producing levels of around 100dB on one side of the wall, around 50dB will still make it through to the other side - and remember that this figure will be worse at the bass end. If you're directly adjoining a neighbour and have just a solid brick wall between you, it's unlikely that the degree of isolation will be adequate if you monitor loudly, and lightweight partition walls or breeze block will fare rather worse.

To give an example of typical SRIs, a light panelled internal door has an average SRI of around 15dB or less, and at low frequencies it will be significantly worse. On the other hand, a brick cavity wall, plastered on the inside, can have an average SRI of better than 50dB.

DOUBLE BENEFIT

If a single wall can reduce the sound leakage by 45 or 50dB, what happens if we use two walls separated by an air gap? You might, not unreasonably, think that 45dB for one wall added to 45dB for the next would give a 90dB figure, which would be terrific. However, the maths doesn't work out quite so simply, and, furthermore, unless the walls are separated by a considerable gap, 'air loading' between the walls reduces the efficiency of the isolation. Even so, approaches to sound isolation based on multiple barriers separated by air gaps tend to be the most successful, and a double structure will invariably perform significantly better than a single-layer barrier of similar mass.

http://www.sospubs.co.uk/sos/feb98/articles/soundproofing.ht...

In order to minimise the impacts of noise, headlights and the sight of passing vehicles to the dwelling facing Gladstone Street, it is recommended that an acoustic wall be positioned alongside the western edge of the access road and ramps. This would be in addition to the acoustic wall on the western property boundary required under the original consent that should also minimise noise from the vents of the basement carpark. The previous consent also required acoustic testing to ensure performance. The acoustic walls and 3.3m landscape strip should substantially reduce affects on the amenity of the adjoining residents.

http://www.canterbury.nsw.gov.au/council/meetings/1999/cbus1...

A Soundproofing Wall System designed specifically for high volume music playback.

http://www.asc-soundproof.com/