There are two types of sound insulation testing required on new build and conversation projects – Airborne and Impact.
Airborne noises are transmitted by air and atmosphere. The main examples of airborne noise are sounds generated via a conversation, Radio or TV.
Impact noise usually propagates through solid materials and result from a shock on them. The main examples of impact noise are the footsteps of a person and the sound of an object falling on the floor, such as children’s toys etc.
As the two types of testing are quite different here is a quick article explaining both types and how the tests are undertaken.
Airborne Sound Insulation Testing
Airborne sound insulation testing is un
dertaken to both walls & floors. Firstly a controlled noise is generated by an amplifier and loudspeaker across a broad range of frequencies. The generated noise is very loud – often in excess of 100dB. Initial measurements are taken using a class 1 sound level meter within the ‘source room’ followed by further measurements in the ‘receiver room’ on the other side of the wall or floor under investigation. The source room speaker position is then changed and the measurements repeated either side of the partition under test.
Thereafter, background noise measurements are undertaken using a class 1 sound level meter in the receiving room and are used to apply appropriate corrections for external sound such as traffic noise. Similarly the reverberation time (the time taken for sound to decay by 60dB) is measured within the receiving room using the sound source and a sound level meter to determine the corrections that must be applied to account for the characteristics and absorptiveness of the room.
The difference in the two airborne noise levels (for walls and floors) are corrected for background and reverberation characteristics of the rooms and determines the airborne sound insulation performance of the wall, or floor. A greater airborne noise difference between the source room and the receiver room determines a higher airborne sound insulation performance.
Impact Sound Insulation Testing
Under Approved Document E, Impact sound insulation testing is usually undertaken to floors only. This test is quite different; a calibrated Norsonic ‘tapping machine’ which comprises of five ‘hammers’ driven up and down by a cam and electric motor is used to “tap” the floor surface by applying a known force on the floor structure. The machine is placed in several pre-determined positions, usually 4 positions with two measurements undertaken in each position. The resulting noise is measured in the dwelling below, using a sound level meter.
Thereafter, background noise measurements are made using a class 1 sound level meter in the receiving room the appropriate corrections applied for external sound such as traffic noise. Similarly the reverberation time (the time taken for sound to decay by 60dB) is measured within the receiving room using the sound source and a sound level meter to determine the corrections that must be applied to allow for the characteristics and absorptiveness of the room.
The measured noise levels in the receiving room are corrected for background and reverberation characteristics determine the impact sound insulation performance of the floor. For the impact noise the lower the measured level, the better the performance as less sound is being transmitted into the dwelling below, which is the opposite to airborne noise measurements.
If you would like more information in regards to this article and/or you simply require sound insulation testing then please contact us now.