Sound Test Terminology (1 of 3)
Often confusion can arise from the large amount of ‘terms’ used in conjunction with acoustic design and sound insulation testing. To help with this we have made a list of the following terms for clarity – this is the first of three blogs:
Absorption – This is the conversion of sound energy into heat, often by the use of a porous material.
Absorbent Material – This is a material that absorbs sound energy, such as acoustic mineral wool.
Airborne sound – This is sound which is propagated from a noise source through the medium of air. Examples of these are speech and sound from a television
Airborne Sound Transmission – This is direct transmission of airborne sound through walls or floors. When sound energy is created in a room, for instance by conversation, some of the energy is reflected or absorbed by room surfaces but some may set up vibrations in the walls and floor. Depending on both the amount of energy and the type of construction, this can result in sound being transmitted to adjacent parts of the building.
Air Path – This is a void in construction elements, which adversely affects the performance of sound resisting construction. Examples of air paths include incomplete mortar joints, porous building materials, gaps around pipes and shrinkage cracks – this can also effect the air tightness results.
Bonded resilient cover – This is a thin resilient floor covering normally of minimum 3-5mm thickness, which is bonded to the isolated screed surface to reduce impact sound transmission such as footfall noise, however it has a lesser effect when it comes to airborne noise.
Cavity stop – This is a proprietary product or material such as mineral wool (fibre) used to close the gap in a cavity wall.
Composite Resilient Batten – This is composed of a timber batten with a pre-bonded resilient material to provide isolation between the flooring surface layers and floor base.
Cradle/Saddle – This is an intermediate support system (with a resilient layer base, either pre-bonded or already integral) using levelling packer pieces to support a timber batten, isolating it from the floor base.
Decibel (dB) – This is the unit used for different acoustic quantities to indicate the level with respect to a reference level.
Density (kg/m3) – This is the mass per unit volume, expressed in kilograms per cubic metre (kg/m3). Blockwork is commonly referred to by industry in terms of strength (in Newtons). However, it is the density that has the important role in terms of sound insulation.
Direct transmission refers to the path of either airborne or impact sound through elements of construction.
DnT,w – This is the weighted standardized level difference. A single-number quantity (weighted) which characterises the airborne sound insulation between two rooms, in accordance with BS EN ISO 717-1:1997
We hope the above information in regards to Sound Test Terminology has been helpful. If you would like more information in regards to our acoustic design or sound insulation testing services, please contact us at firstname.lastname@example.org or visit our website at: www.aptsoundtesting.co.uk