Objectives and content
Quality and comfort of private and public buildings is -
to a considerable extent - assessed by the acoustic
climate inside the building. Disturbing noise comes
through windows, doors and lightweight internal walls
with poor sound insulation capacity, especially at low
frequencies. Disturbing reverberation and reflections are
often present in public buildings with large areas of
hard walls and ceilings, but also in private living rooms
reverberation and reflections can severely prevent good
music listening conditions. The increase of sound
insulation of walls, windows and doors is essential in
increasing the quality of the acoustic environment.
Traditionally this is done by increasing the thickness
and weight of walls and door panels, increasing the
absorption material inside double leaf partitions and
increasing the number of glazing layers of windows.
However, these add weight and cost of building elements
and make the construction complicated.
The main industrial objective of the research is to
demonstrate a major breakthrough in the development of
active control of sound (ACS) systems for buildings.
They can increase the comfort and reduce the thickness,
weight and cost of building elements. This can be
achieved by using high efficient flat film actuators as
anti-noise sources. The technical innovation,
ElectroMechanical Film (EMF) can be used as an acoustic
source. The actuators made of EMF are very thin, weigh
very little, are mass-producible and thus cheap. They
can be placed on all desired places on walls and ceilings
and inside double leaf partitions. In existing buildings
noise reduction using ACS can be more efficient and
extended to higher frequencies. In future buildings
light-weight panels on which the EMF actuators are fixed
can have acoustic transmission loss as high as the
transmission loss of existing high-weight panels.
The easy integration of low-cost EMF-actuators in ACS
system can make the ASC systems extremely feasible in the
control of low frequency noise in buildings. The main
drawback with older ANC systems have been that they have
not been compatible with mass-production and the price of
the systems have been high.
The technical objectives of the research are to
investigate, design and develop four generic active
actuators and combine them to traditional building
elements to form three prototypes.
The first prototype is an active absorbing EMF element
combined to a traditional thin passive absorbing element.
With this kind of combined active/passive elements the
absorption coefficient of thin layers at low frequencies
can be as high as of very thick and heavy passive
materials. Furthermore, with active elements we can
change absorption coefficient electrically and create
even delay effects for optimising the acoustic
environment for comfort.
The second prototype is a light-weight active sound
insulating panel based on EMF-technology. It can be
utilised for the sound insulation increase of nontransparent boundaries, such as doors and light-weight
internal walls. The sound insulation increase using
active elements is expected to be several (even tens) of
decibels at low frequencies without excessive addition of
The third prototype is the most ingenious one, because it
will be designed for transparent boundary applications,
such as increasing the sound insulation capacity of
windows. It is based on the idea that passive shutter
blind elements can be made of active EMF-material and
these actuators can produce the needed anti sound between
the double glazing window. It may even prove feasible to
use them as anti noise sources for open windows.
The demonstrations of effective ACS systems in buildings
will disseminate the technique also to other sectors, for
instance, to household appliance noise control and even
to industrial machinery noise control.
Funding SchemeCSC - Cost-sharing contracts
100 44 Stockholm