THURSDAY, OCTOBER 17, 2019
Engineering a new type of wall, and then we can all get some sleep
Researchers at the University of Auckland have been awarded close to $1 million to develop a new type of wall, to better
shut out the unwanted sounds of the people next door.
This is timely. We’re living in an age of increasingly powerful entertainment systems and often forced to listen to
other people’s music, televisions etcetera, which can affect our health and well-being.
Moreover, the acoustic intrusion of our neighbour’s is more likely in medium-density housing, which is projected to
constitute 30 percent of Auckland’s housing by 2050.
The team of mechanical engineers at the Faculty of Engineering’s Acoustic Research Centre, awarded $991,000 from the
Ministry of Business, Innovation and Employment (MBIE), is taking an innovative approach to noise insulation.
They aim to create a new kind of partition material in which they, with the use of specific materials, will reduce the
capacity of a wall to vibrate in response to sound, thereby providing better sound insulation, but without taking up
more floor space.
They are particularly focussed on cutting out low frequency noise, which travels more easily through walls – other
people’s bass beats, for instance, which can be intrusive and impossible to ignore.
“Sometimes it feels like Sting is playing his bass in your living room,” says Dr Andrew Hall, who is leading the
research, adding that he likes Sting’s bass playing “just not at 2am”.
A wall is vibrated much more easily at low frequencies, where wavelengths can be more than three metres, Dr Hall
explains. “It’s like a giant hand pushing on the wall.”
Achieving effective noise insulation against low frequency sound is both challenging and expensive, and usually involves
increasing the density, mass or thickness of the partition material.
However he, co-researcher Dr George Dodd and their team have shown through previous research that they can use internal
mechanisms, known as acoustic metamaterials, which can push back against that vibration, and disrupt the sound waves
traveling through the walls.
They are also investigating the use of Helmholtz resonators to improve the noise insulating properties of a wall. “They
respond much like when we blow over the top of a glass bottle, and so absorb and reflect sound,” says Dr Hall. Using 3D
printing of soft and hard materials, the researchers will explore the many possibilities in the design of these
Helmholtz resonators and acoustic metamaterials.
We need and can find technological solutions to protect us from other people’s noises, says Dr Hall. “Despite people
decrying the poor quality of multi-family housing in lower socio-economic sectors, there’s little evidence of research
groups seeking solutions in the innovative way that we are proposing.”
“Our system aims to raise NZ’s sound insulation standards to meet the internationally recognised minimum performance
expressed in overseas building codes. More and more people are living in urban settings in close proximity to others,
and tackling noise pollution will have enormous benefits for their health and well-being.”
ends