Karma Acoustic Solutions - Explanation of Terms
There are a number of complex terms and measurements that are used in the field of construction acoustics. This explanation of terms has been created in order to facilitate easier understanding when compiling or interpreting acoustic specification.
Useful Information
Attention to detail is vital, as one incorrectly installed
component can cause a whole element to fail. Particular
attention should be paid to potential flanking paths and
all acoustic bridges such as services, downlighters and
joints should be sealed with specialist acoustic products.
These are featured in the ancillaries section of this guide.
| Term | Definition |
|---|---|
| Building Element | Wall, floor, roof etc. |
| Ctr | The correction factor used in Approved Document E to place a greater value on low frequency sounds which are easier to detect by the human ear |
| Decibel (dB) | The most communally used unit to measure sound, the decibel is measured on a logarithmic scale, therefore although 10dB does not sound like a great difference it equates to around a 50% reduction in the level of sound that the human ear would detect |
| DnT,w | The measurement used for airborne sound insulation between two rooms (on-site) |
| DnT,w + Ctr | See above, but with the low frequency correction factor included |
| Flanking Transmission | Sound transmitted between two rooms using an indirect path i.e. the top or bottom of a separating wall |
| Hertz (Hz) | The unit of frequency of sound |
| Impact Sound | Sound resulting from direct impact on a building element |
| Internal Floor | Any floor which is not a separating floor |
| L’nw | The measurement used for impact sound insulation of floors (in the laboratory) |
| L’nT,w | The measurement used for impact sound insulation of floors (on site) |
| ΔLw | Denotes the measured improvement of impact sound insulation resulting from the installation of a floor covering or floating floor |
| Rw | The measurement used for airborne sound insulation between two rooms (in the laboratory) |
| ΔRw | Denotes the measured improvement of airborne sound insulation resulting from the installation of a product to a wall or floor |
| Separating Floor | Floor that separates flats or rooms for residential purposes between adjoining properties |
| Separating Wall | Wall that separates flats or rooms for residential purposes between adjoining properties |
| Sound Reduction Index (SRI) | A quantity measured in a laboratory that characterises the sound insulation properties of a material or building element in a stated frequency band |