Acoustic certificates
To determine the exact absorption behaviour of products it is necessary to have them measured in a reverberation room. For this reason, the majority of our acoustic elements have already been tested in a certified reverberation room of the Technical University Graz. All current certificates are available for download on our homepage. Below, you will find an overview and explanations of the most important terms of certification.
Go to certificatesOptimised sound absorption
The absorption of sound significantly influences the noise level in a room. The degree of absorption indicates how much sound individual materials and objects reflect or absorb. Sound absorption directly influences the reverberation time in a room, which has a positive effect on the noise level. The harder and smoother a material, the lower its absorption. The value ranges from 0 – complete reflection – to 1 – complete absorption and usually differs according to frequency. In room acoustics, we pay particular attention to the frequency range from 125 Hz to 4000 Hz. Based on this, we then calculate the reverberation time and design the ideal spatial acoustics solution.
Alpha W and sound absorption classes
The Alpha W (weighted sound absorption coefficient) is an average value of sound absorption that is particularly commonly used in German-speaking countries. When calculating the Alpha W, the uniformity of absorption across all frequency ranges is also considered.
Based on their Alpha W, materials or objects are divided into classes A to E, with A indicating the highest degree of absorption. The absorption class is only used for a rough classification of absorbent materials or products. Since the distribution of absorption over all frequency ranges is crucial in spatial acoustics planning, these must be considered in the calculation.
NRC et SAA
These two parameters are used to roughly assess the effectiveness of acoustic products. The NRC (Noise Reduction Coefficient), which is mainly used in English-speaking countries, is the average sound absorption coefficient in the range between 250 Hz and 2000 Hz. The SAA (Sound Absorption Average) averages the absorption coefficients in the range from 200 Hz to 2500 Hz. More values are included and the results are less rounded than with the NRC. In the long term, it is expected that the SAA will replace the NRC.
Absorption Area
The equivalent absorption area plays an important role in calculating the reverberation time in enclosed spaces. The larger the area for an assumed 100 per cent sound absorption, the shorter the reverberation time. This absorption area is calculated by multiplying the absorption coefficient by the surface area of the object. For example, 1 m² of carpet with an average absorption coefficient of 0.5 has an average absorption area of 0.5 m². For complex three-dimensional objects, calculating the absorption area can prove difficult, so the specified absorption area is multiplied by the number of products used.
