Acoustic Testing
The only way to determine the performance of a particular doorset design is to test that product, installed into a structure in a manner that replicates precisely the methods intended for use.
Test Methods
The BS EN ISO 10140-2: 2010 test involves placing the door construction within a dividing wall between a sound source room and a receiving room. Sound waves are produced in the source room and measurements of the sound pressure levels are made in both rooms at one-third octave intervals in the frequency range 100 to 3150 Hertz (Hz).
Several microphones are used to obtain a good average of the sound pressure level in each room. From these measurements, the Sound Reduction Index (R) is derived.
These values are then calculated in accordance with BS EN ISO 717-1: 2013 to obtain as single figure weighted sound reduction index (Rw). The ASTM method follows the same principle but performance is measured over a slightly different frequency range, 125 to 4000 Hz and the results are expressed as a sound transmission class (STC).
Terms
dB Decibel. A comparative figure generally indicating a decrease in sound level between two points (source and receiver). The dB scale is logarithmic so 10dB is 10 times the power ratio, 50dB is 100,000 times the power ratio and 100dB is 10,000 000 000 times the power ratio of 1dB respectively.
R Sound Reduction Index. Expressed in dB and defined as the number of decibels by which sound energy, randomly incident on the test sample, is reduced in passing through it.
STC Sound Transmission Class. A single figure performance indicator very similar to Rw but derived from ASTM-E413-10. Classification for rating sound insulation. The Rw or STC rating indicates acoustic performance of a door/seal assembly over a wide spectrum of sound frequencies.
Test Reports
Documented test evidence is required to verify the acoustic performance of a door assembly. When looking at any acoustic test report for a doorset or sealing system, it is important to remember the relationship and inter-dependency between the door, frame and sealing system. The wall, floor and ceiling construction will also influence performance.
Door manufacturers' test reports should always indicate how the door perimeter was sealed, including the threshold.
Seal manufacturers' test reports should always indicate the kind of door used to evaluate the sealing system and indeed if a real door was used at all. It is advisable to carefully inspect test reports to determine whether a real or full-size operational door assembly was actually tested or smaller sections and portions of the door.
All Lorient sealing systems are acoustically tested in their everyday operational mode. Under laboratory test conditions, it is all too easy to achieve deceptively more impressive results by wedging a door leaf in the frame with the seals in an extreme, highly compressed state – even if the operation of such a door in everyday service would be untenable. Lorient results are truly indicative of practical expectations.
Regulations + Requirements
Building Regulations exist to ensure the safety and comfort of everyone using a building. Various documents demonstrate the usual way of meeting the requirements of the Building Regulations and in many cases give specific guidance on acoustic containment, accessibility and fire and smoke containment.