Sound Science

Scientists in Auckland are figuring out the best way to soundproof our timber houses.

"It is hard to imagine there is any high technology involved in taking a pile of 4 x 2's, a heap of nails and plasterboard and making a house," said research leader Keith Ballagh.

"But we have been using very sophisticated techniques to study how sound is transmitted through a typical timber framed New Zealand house, to understand why some timber framed houses have very poor sound insulation.

"Recent trends in housing are away from single houses to apartments and other multi-unit dwellings these put people very close to each other, often with potentially incompatible life styles."

The research, an investment of the Foundation for Research, Science and Technology, stems from the requirements of the New Zealand Building Code.

This code requires architects and builders to meet certain standards of sound insulation between different buildings.

"Although builders and architects know about the code there is a lack of knowledge on how these sound conditions can be achieved, especially in common timber framed buildings," said Mr Ballagh.

"While walls or floors by themselves can be measured in special laboratories, there is no information on how sound behaves at the junctions between walls and floors, or how sound can travel along floor joists under a wall and into an adjacent room.

"Such information is absolutely crucial for designing successful buildings that are quiet and soundproof.

"We have been studying sound waves traveling in timber beam and plates by measuring the tiny vibrations that carry the sound energy. By using lots of measurement points and analysing this data with sophisticated software, a lot of understanding can be gained as to how the sound waves travel around bends, through nailed joints and across connections."

By putting this knowledge into mathematical models, the researchers can then predict how sound will penetrate walls in homes.

"The next step will be to find ways of reducing this transmission simply and cheaply so that we can continue building with our traditional materials such as timber and plasterboard and have quiet sound-proof houses," said Mr Ballagh.

For further information: Keith Ballagh, Marshall Day Associates, Tel 09 379 7822 keith@marshallday.co.nz Madeleine Setchell, Communications Adviser, Foundation for Research, Science and Technology Tel 04 9177806 Mobile 025 40 60 40, www.frst.govt.nz

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