Optimally insulated for greater comfort
We are affected by noise throughout the day, and often this cannot be avoided.
However, with the right insulation, noise emissions can be reduced and the quality of life in living and work areas can be considerably improved.
With their open pore fibre structure, our Mineral Wool products provide the ideal conditions for absorption and regulation of noise and are therefore ideally suited for comprehensive sound insulation.
Knauf Insulation Sound-teK Products
Sound absorbing effects of Mineral Wool boards
Due to their open / fibered structure Mineral Wool insulation material perform on good sound absorbing characteristics. Sound absorption is described by the capability of material to reduce the intensity of in-coming sound and not to reflect it to the environment- so-called the sound-absorpant behaviour.
The specific and individual interpretation, based on material thickness, weigth and potential surface treatment can be pretty complex for installers due to the complexity of acoustic applications.
The sound absorbing impact of material is described by the sound absorption value; the so-called "practical sound absorption degree" describes the sound absorption capacity of a material at six frequences in octaves. The values are between 0,0 and 1,0; where 1,0 is the total absorption of in-coming sound in the considered frequence area. Values bigger than 1,0 are not possible.
The decision criteria for sound absorption results of Mineral Wool insulation material are
- the weight
- the surface treatment: faced or un-faced
- the insulation thickness
The facing needs to have an "open structure", like e.g. single-faced (VBS) or double-faced glass fleece (VBD) or glass woven (WBS or WBD). The "closed structure", like aluminium foil (ALU) is not able to absorb the sound, but reflects it.
Acoustic noise characteristics
Perception and impact of sound noise / Sound characteristics
Sound noise are described by mechancial vibrations and waves. The extenstion of sound in the air is described as airborne noise, the one in solid material solid-borne noise. In a vacuum there is no sound transmission possible.
Individual sound perception
The characteristic measurement for the perception of sound by the sense of hearing is the acoustic pressure as well as the frequency. The physical unit for acoustic pressure is Pascal (Pa), the one for frequency is Hertz (HZ). This means that 1 Hz = 1 wave per minute.
The frequency determines the pitch, the pressure the volume.
The frequency range of 16 - 16000 Hz (typical range of audible of an human ear) is divided logarithmically into octaves and third-octaves.
Frequence spectrum at octave and third octave band
|Octave band||fm, octave||31,5||63||125||250||500||1000||2000||4000||8000||16000|
|Third octave band||fm, third octave||31,5||40||50||63||80||100||125||160||200||250|
Criteria curve A
A rating curve
The sound perception is individual from one to another on the frequency. For that reason there are defined four different weigthing curves based on the frequency weigthing of acoustic events. The most common curve for frequency-related weigthing of acoustic events is the internationally agreed weigthing curve A. Levels that are rated by that curve are described with the unit dB.
Calculation of A sound pressure level
A sound level curve
Calculation of the A-sound pressure level out of the octave band range, e.g. gas engines, 300 kW, 1.500 * 1/min, 1m at exhaust pipe.
The table shows the differences between A-reated and un-rated levels of an gas engine.
|Octave band medium frequence||31,5||63||125||250||500||1000||2000||4000||8000||Sum|
|measured sound level [dB]||91||92||93||94||95||96||92||88||83||102,3|
|rated sound pressure level [db(A)]||51,6||65,8||76,9||85,4||91,8||96,0||93,2||89,0||81,9||99,5|
Advantages of Mineral Wool