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Building Products March 2018

INSULATION AND ACOUSTICS From light to air movement, fire safety to access, the specification of any acoustic material must strike the right balance between functionality, effectiveness and aesthetics. Here, Mike Carrick, head of acoustics at Siderise, looks into the art and science of acoustics. Acoustics, like lighting, should be an integral part of good architectural design, but every space represents a unique acoustic challenge, whether it is an office, school, hotel or apartment building. When it is done well, it is a significant contributor to the well-being and productivity of building occupants. While materials in a room including furniture, floor coverings and even computer screens can affect sound levels to one degree or another, wall partitions, ceiling systems and acoustic void barriers are the principal architectural elements that designers use to control sound. From the outset it’s important to use materials which will achieve good acoustics and solve any sound transmission issues while not compromising the aesthetics of the interior space. 34 BUILDING PRODUCTS | MARCH 2018 The designer must also not only satisfy the legislative requirements, but the client or end user’s ‘wish list’ of acoustic behaviour. Proper acoustics, the unobtrusive sum of all sounds, is the key objective for a comfortable environment. Common voids The sound separation achieved between adjoining rooms or offices is often severely limited by ‘crosstalk’ via a common void. This common problem occurs when the transmission loss associated with this sound path is less than that provided by the primary separating element, for example, a partition. Voids affected by ‘cross-talk’ include: • Suspended ceiling voids at partitions • Access floor voids below partitions • Cavities at floor slab edges to facades. To effectively reduce sound transmission or ‘cross-talk’ via hidden voids which sit above office partitions, ceiling void barriers should be installed directly in-line with the partition. The Sound Reduction Index or SRI (Rw) of the cavity barrier is not normally required to equal that of the partition itself. This is due to the presence of other obstructions in the room-toroom sound path such as the suspended ceiling. The individual performance of the barrier need only be sufficient to correct the shortfall between the partition and the untreated cross-talk path. Ceiling systems The actual value of these paths can vary substantially. For ceiling voids, 15-40dB Dnf,w (DnCw) would usually be associated with most suspended ceiling systems. An acoustic engineer THE SCIENCE OF SOUND


Building Products March 2018
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