Sound insulation

Lately, we experience a growing demand for better sound insulation besides thermal insulation concerning the doors and windows of our homes. A few years ago, sound insulation had significance only when huge projects or office buildings were constructed. In contrast, today, sound insulation receives more attention during the replacement of doors and windows for residential buildings.

Since glass makes up a large surface area of doors and windows, it is important to choose the most adequate glass construction to increase their value.

The larger the dB value of an insulating glass unit, the better its sound insulation qualities.

Sound insulation is marked with Rw, its unit of measurement is decibel (dB). In order to get a clearer picture of what different values mean, we brought some ordinary examples to illustrate:

Not disturbing noises
Raining 20dB
Whispering 30dB
Listening to the radio (on a normal level) 40-50dB
Normal conversation 60dB

Disturbing noises
Phone ringing “typewriter” 70dB
A busy road in a city 80dB
Jackhammer 90-110dB

Noises causing pain
Helicopter 120dB
Subsonic jet airplanes 140dB

How can we protect ourselves from the above mentioned noises?

A simple example:
The noise from which we want protection is 60dB.
We do not want noises higher than 20dB.
Consequently, we should choose a glass with 40dB value.

Change in dB values, as perceived by humans:
+ 1 dB, scarcely perceptible
+ 3 dB, perceptible
+ 5 dB, significantly perceptible difference
+ 10 dB, perceived as if noise is doubled

The sound insulating ability of the glass can be improved by various methods.

The simplest way is to exchange one 4 mm glass for a 6mm thick glass in the standard glass structure (4mm – 16 spacer – 4mm) on one side. It is advisable to place the thicker glass on the side of the noise. This simple change in the structure can raise the Rw value with 5dB.

Furthermore, by increasing the thickness of the glass, the Rw value will improve as well.

Be careful! By increasing glass thickness, the weight of the glass unit will significantly increase too.

Nevertheless, increasing the glass thickness is not the best solution when there is a need for a higher sound insulating ability. To meet these demands, glasses with a special sound insulating foil were developed.

In this case, not the traditional security foil is laminated between the two glasses, but a special one that besides being a security foil, also has the ability to extremely dampen sound.

By increasing the number of foils and the thickness of the glasses, the sound proofing ability will also improve. For custom needs, unique factors must be considered In every case, the Rw value shows the weighted sound reduction index of the unit. This means that the structure is tested under 16 different frequency ranges between 100 and 3200 Hz. The results are aggregated (the typical ones are more relevant, the atypical ones considered less) and we receive the weighted sound reduction index, the Rw of the structure.

Besides marking the weighted sound reduction index, very often the Rw+Ctr value is indicated. “Tr” comes from the word traffic. The Ctr value is typically less than the weighted sound reduction index. The Ctr value shows the sound reduction index of the structure in a given frequency range arising from traffic and street noise.

For custom needs, unique factors must be considered

In every case, the Rw value shows the weighted sound reduction index of the unit. This means that the structure is tested under 16 different frequency ranges between 100 and 3200 Hz. The results are aggregated (the typical ones are more relevant, the atypical ones considered less) and we receive the weighted sound reduction index, the Rw of the structure.

Besides marking the weighted sound reduction index, very often the Rw+Ctr value is indicated. “Tr” comes from the word traffic.

The Ctr value is typically less than the weighted sound reduction index. The Ctr value shows the sound reduction index of the structure in a given frequency range arising from traffic and street noise.

IMPORTANT!

Take into consideration that by increasing the distance from the source of the noise, the absorbed noise will decrease proportionally.

In practice, the noise will decrease in the following way:

with 3dB at a distance of 10 m from the source of the noise
with 6dB at a distance of 20 m from the source of the noise
with 9dB at a distance of 40 m from the source of the noise
with 12dB at a distance of 80m from the source of the noise
with 15dB at a distance of 100 m from the source of the noise

In order to effectively protect ourselves from special noises, first we need to know the frequency range of the source of the noise. To know this factor is quite relevant since we should find the best solution in the given frequency range, and not necessarily in the weighted average.