Acoustic testing of doors according to American STC: Reverberation chamber test method for determining sound insulation.


The standards used for a determination of the STC value are:

ASTM E90-09 “Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements”.

ASTM E413-10 “Classification for Rating Sound Insulation”.

ASTM E1332-16 “Standard Classification for Rating Outdoor-Indoor Sound Attenuation”.

ASTM E 2235-04 “Standard Test Method for Determination of Decay Rates for Use in Sound Insulation Test Methods”.


The calculation of the STC (Sound Transmission Class) index, according to the E413 standard, is based on the calculated values for each one-third octave frequency band from 125 Hz to 4000 Hz. The experimental curve is evaluated and compared with the reference curve.

Then the curve comparison method is applied up to the point where the sum of the unfavourable differences between the relative curve values are on the reference curve less than or equal to 32 dB and the maximum deficiency at any one frequency does not exceed 8 dB.

The single number evaluation is given by the value of the reference contour shifted to 500 Hz.


The classification, according to the E1332 standard, requires the measurement of Transmission Loss (TL) in the third octave band from 80 to 4000 Hz for the determination of the Outdoor-Indoor Transmission Class (OITC) index.

The same port tested for Rw and STC could give similar results, although sometimes American results are slightly more ‘optimistic’ than European ones. By changing the band and the method, they may go


Many door manufactures come to us for making tests for their products, finalized to be used as evidences for the certified body for CE marking, in order to obtain the fourfh digit.

We can carry out fire tests as follows:

  • activities for customers, where in accordance with the parties we insert products of the manufacturer of accessories;
  • dedicated activities, where we arrange everything , even the doors on which to mount accessories.

It goes without saying that the second type of activity, on the one hand guarantees results, time and ownership of evidence, on the other hand has higher costs.

We can also find evidence from our extensive database, possibly agreeing to allow the use of the same for marking or EXAP. In the case of evidence in our possession, the agreement is made directly with us. In the case of evidence from customers, we check whether there is a willingness to agree with the relevant guarantees.

On the subject of EXAP we can prepare the request to the laboratories. 

On the subject of HPS, we can provide the drafting.

The fire tests can be according to EN1634-1 or EN1634-2, see the TESTING section of our website for specific insights.