What is Sound Testing?
Sound Testing is a requirement to test the volume of sound measured in decibels through walls and ceilings of new structures. Tests must be carried about by a UKAS or ANC accredited body.
Why do we do Sound Testing?
Part E (2003) of the Building Regulations Approved Documents stipulates that sound insulation testing should take place in all residential developments that involve party elements (walls and/or floors). This applies to all new-build or converted residential developments in the UK, where a minimum sample of 10% of properties require sound insulation testing. The end result of sound testing is to provide the end resident with a better quality of living from reduced sound transfer through floors and walls.
The specific performance requirements for new builds and conversions are set within Approved Document E (2003 Edition) and are summarised in the following tables.
| Purpose Built Dwellings Conversions | |
|---|---|
| Airborne Sound Insulation(DnT,w + Ctr) | > 45 dB |
| > 43 dB | |
| Impact Sound Insulation (L’nT,w) for floors only |
< 62 dB |
| < 64 dB |
Test Procedures
In order to have analysable results, two measurements are needed in order to correct the results for receiver room characteristics. These are the background noise of the receiver room and the reverberation time of the receiver room. As well as these characteristic data, the actual airborne or impact tests are undertaken.
Background Noise
The background noise in the receiver room is measured so that the sound insulation test results are corrected for external sound, such as traffic noise. The background noise is taken into account when calculating the sound insulation rating for the party element.
Reverberation Times
The reverberation time of receiver rooms is measured so that corrections can be applied to account for the characteristics and absorptiveness of the room. In each room, the reverberation time is calculated six times and an average is taken.
To measure the reverberation time, a speaker is used to generate white noise in such a way to create a diffuse field. The speaker is then instantaneously switched off, and the time taken for the noise in the room to drop by 60dB is measured. The average of the six measurements is applied to the calculations to determine the sound insulation performance.
Airborne Testing
In order to rate the airborne sound insulation of a party element, speakers are used to generate white noise, usually at levels of around 100 decibels, in the source room. Then, using a moving microphone technique, the average sound pressure level is measured. The same procedure is used to measure the average sound pressure level in the receiver room.
From these measurements, combined with the background and reverberation time measurements, the airborne sound insulation of the party element can be calculated.
Impact Testing
Impact tests require a tapping machine to create impact sound directly on the floor construction in the source room. Measurements are taken in the receiver room, in third octave bands from 100Hz to 3150Hz. The impact sound pressure level is calculated, giving the floor an impact sound insulation rating.
Measurements are taken with the tapping machine in at least four different position and at least six measurements are taken.
This gives six results which can be used along with the background noise and reverberation time of the source room, to calculate an impact sound insulation rating.