Glyntaff Crematorium Acoustic Doors
QuietStar recently installed a bespoke double acoustic doorset at Glyntaff…
How do soundproof windows work?
We are often asked questions like: How do your soundproof windows work? How do you manage to get such high levels of acoustic isolation?
In short, the answer is we’re geniuses…and use the best possible materials…and install everything correctly…and most importantly…we work with customers to choose the best possible solution.
What components are used in acoustic windows?
There are 5 core components in a good quality acoustic window. These are the glass, frame, air gap (for double glazed units) seals and reveal.
When performance is key, then steel is king. Like a lot of good quality soundproofing products, the denser they are, the better they are at isolating soundwaves. Steel as a frame choice is often critical to achieve the performance levels required for acoustic studios or hearing testing rooms.
Because of its inherent strength, steel is also a great choice for safety applications such as fire rated windows, bullet resistant & blast rated.
In addition to a strong steel frame, the choice of glass is the next most important component.
Glass used in acoustic windows is different to regular glass found in double glazing applications. Instead, the glass is laminated using at least two sheets and bonded together to improve strength and mass. In doing so (and depending on the performance required), acoustic glass is normally quite thick and very heavy. As a rule of thumb, the thicker the glass, the better the acoustic isolation.
Soundproof windows typically consist of two laminated panes of glass with an air gap in between. The air gap is normally dictated by the thickness of the host wall. This is why in studio applications, to get the amount of isolation required, the walls are much thicker than you would typically find in a conventional building. The air gap plays an important role in achieving high acoustic performance levels, along with the absorptive reveal.
The reveal is the area in between the two panes of glass and is usually manufactured from an acoustically absorptive foam. This serves two purposes, to hide the fixings used when installing the frame, and provide an additional level of acoustic absorption.
To further improve the performance of a soundproof window, additional panes can be added making a unit triple or even quadruple glazed. Adding additional panes of glass can improve impedance. Put simply, the thicker the glass, or by using a greater number of panes is a highly efficient way of breaking soundwaves up and improving acoustic performance.
How are soundproof windows installed?
Installing an acoustic window usually takes a lot of manpower and heavy lifting. Depending on the opening, the glass alone can weigh 100kg+ and the steel frames can also take multiple people to manoeuvre into position.
Because of the weight and size, acoustic windows are almost always manufactured as a kit and assembled on site. To reduce any vibration and potential structure borne noise, soundproof windows are normally installed in such a way that they are acoustically isolated from the host wall. This is done using rubber seals and gaskets so the contact between the frame and wall are minimised.
Sound is similar to water in that it will always find a way to leak out, even if this is only by a small amount. Because of this, any soundproof window must be perfectly sealed on both sides to ensure maximum performance.
How to get the best performing acoustic window?
To get the best possible (or most achievable) performance, there are a few factors to consider. What is the acoustic performance of the host wall? If the existing wall only has an acoustic performance of 55dB, then using a 65dB window would not improve the overall room performance.
The focus must be on getting a window to perform at least as good as the host wall, but without going over the top.
The construction of the wall will have an impact on how a soundproof window is designed and installed. We mentioned the air gap earlier.
If the thickness of the wall is relatively thin (less than 100mm) then typically, the glass will need to be thicker to achieve the same acoustic performance as a wall that is 200mm think. This is because the air gap is a great way of reducing low frequency noise which is more difficult to achieve using mass alone.
The exact acoustic performance required can be achieved using a range of different glass thicknesses and air gap sizes. The exact combination is often bespoke to suit the application.
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