CMS Danskin Acoustics for Architects

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Acoustic Terminology

Absorptive Material Material that absorbs sound

Airborne Sound Sound propagating through the air. Often linked to speech, media equipment, etc.

Building Element Walls, floors and roofs etc.

Ctr The spectrum adaption term to take account of specific sound spectra, which are predominantly low frequency. Only used as a correction to airborne measurements.

Decibel (dB) The most commonly used unit to measure sound.

dB(A) Unit of sound weighted to the human ear.

DnTw The measurement used to measure the airborne sound insulation between two rooms (on site).

Dntw + Ctr See above, but with the low frequency correction factor included.

Final Floor Finish Carpet, vinyl, laminate or other top floor finish.

Flanking Transmission Airborne sound or impact sound transmitted between two rooms using an indirect path i.e. the top or bottom of a separating wall.

Floating Floor Treatment Often referred to as “FFT”. An FFT may use battens, cradles or platform base all of which use a resilient layer to provide isolation from the base floor.

Floating Layer A surface layer that rests on a resilient layer.

Frequency The number of pressure variations per second that gives a sound its distinctive tone.

Hertz (Hz) The unit of the frequency of the sound – also known as “Cycles Per Second”.

Impact Sound Sound resulting from direct impact on a building element.

Internal Floor Any floor that is not a separating floor between dwellings.

Internal Wall Any wall that does not have a separation function between dwellings.

LnTw The measurement used to measure the impact sound insulation of floors (on site). =Lnw laboratory testing.

Noise Unwanted sound.

Pre-Completion Testing (PCT) A new requirement to Part E where structures not conforming to the

RSD will be tested prior to completion to check they reach the required standards.

Resilient Layer A layer of resilient material that isolates an element (e.g. screed, floating floor) from another element (base floor).

Robust Standard Detail (RSD) A collection of pre-approved constructions that, if used, negate the need for PCT.

Rw The measurement used to rate the airborne sound insulation of a material or building element in a laboratory.

Separating Floor A floor that separates adjoining dwellings.

Separating Wall A wall that separates adjoining dwellings.

Structure Borne Sound Sound, which is carried by the structure of the building.

Underscreed Material A layer of resilient material (E48, 6010BA, & SH) fitted beneath a floating screed. The resilient material sits on either a hollow core or block and beam base to provide impact sound attenuation.

To speak to our acoustic experts, call 01925 577711 or email us at [email protected]