Is the Lab Testing Data Realistic?

Each manufacturer of sound-proof chambers, sound insulation materials and sound absorbers specify their sound absorbing coefficient and sound transmission loss (STL) as published data. Sonora Technology also specifies the acoustic performance value of our products. However, those data don’t often work for comparison in reality.

[1st Mistake] Data from different measurement methods have been compared.

There is more than one method to measure sound absorption coefficient and sound transmission loss. Therefore, the following issue may occur.

It is not correct to recognize that the material B has a higher sound absorption coefficient than the material A!

There is no point unless they are compared using the same measurement method.

It would be possible that it is 0.99 when the material A was measured by the reverberation chamber method. In that case, it goes without saying that the material A has a higher sound absorption coefficient than the material B.

【2nd Mistake】Data from different measurement conditions have been compared.

The data obtained using the same measurement method on the same measurement target may differ depending on the measurement location and environment. The data measured in laboratory A and laboratory B using the reverberation chamber method may also be different. The data may be impacted by the dimensions of test facilities, the degree of reverberation, the temperature and humidity. The measurement itself would be denied to go that far though, the data should be understood as reference value only.

【3rd Mistake】Misconception that the data should be the same in the laboratory and on site

Even though the transmission loss of a material measured in the laboratory is 30 dB@500 Hz, this does not mean that the sound transmission loss will be as per the data when the material is used to construct on site. In fact, a drop to 20 dB @ 500 Hz may be quite possible, since the amount of usage and the environment differ between the laboratory and the site.

Summary

As already explained, lab testing data is not necessarily realistic. The data is for comparison, but we should be aware of the above-mentioned 3 points.