Noise Control (ANC)
MSC offers its clients Adaptive
Noise Control solutions which, in certain situations,
can be a highly efficient way to decrease low-frequency
noise that is very difficult and/or expensive
to control using passive means.
What is ANC?
Adaptive control is sound
field modification, particularly sound field
cancellation, by electro-acoustical means. Adaptive
noise control (ANC) is achieved by introducing
a canceling “anti-noise” wave through an appropriate
array of secondary sources. This produces a
sound field that is an exact mirror-image of
the offending sound. The speaker and/or actuator
thus cancels the sound or vibration signal introduced,
while dependent on the situation, can result
in dramatically reduced sound levels.
Due to the availability of inexpensive microprocessors,
ANC - where an interfaced sound wave or vibration
is used to reduce the noise and/or vibration
level, most effective on the low end frequency
range, can reduce the noise/vibration at its
The two forms of ANC that
are currently in use are "Airborne ANC"
and "Vibration ANC":
- ANC - Vibration
ANC vibration system cancels vibration by
generating mirror-image signals of the unwanted
vibration, feeding them back through the microprocessor
to the source 180% out of phase, canceling
the vibration at the source. Going to the
source of the problem these ANC systems eliminate
the need for heavy vibration materials to
be used after the fact. On boats and cars
this translates into "lighterweight"
fuel efficiency at new levels.
An example of this would be an ANC application
for an engine mounting system that would eliminate
the resulting engine vibration from entering
the frame and in turn other components.
- ANC - Airborne Reduction
use's speakers, microphones and controllers
in a controlled "spatial air-field"
These airborne systems are current most effective
in ventilation systems, mostly in office buildings.
The ANC airborne system work in this manner.
The system consisting of two microphones,
a loud speaker and a microprocessor controller.
The controller analyzes noise picked up by
the microphones, processing a 180-degree out-of-phase
antinomies that is played through loudspeakers
to cancel the offending noise.
Where can ANC be utilized?
Weight/space sensitive applications
such as boats are ideal instances of where ANC
can be a highly recommended alternative to traditional
means of controlling low frequency noise situations.
The traditional approach
to attenuate acoustic noise uses passive material
techniques such as enclosures, barriers and
silencers. These passive techniques are suitable
and are preferred for high frequency noise applications.
However to effectively reduce low frequency
noise situations they often need to be relatively
large, very heavy, and costly to manufacture.
In applications where weight
and space are not an issue, these passive techniques
may be acceptable and are relatively easy to
design and build. However when weight and space
are at a premium, such as in the transportation
(cars, boats, airplanes) ANC can be a more effective
MSC and Adaptive Noise Control
This technology is moving
out of the laboratory as companies begin to
develop products that curb noise pollution in
the environment and the work-place. This technology
is still very new and very expensive to develop
in one off applications, but there are generic
products that can sometimes fit your needs.
Trust that MSC will provide you with the best
ANC products and solutions for your needs.
MSC has been actively researching
this field since 1990 and our engineers have
followed this technology from its inception.
If ANC is the best solution for your particular
situation MSC can provide with the services
Questions or for more Information please
17 Birchwood Road
Augusta, Maine 04330
Innovative, functional, cost-effective
products and solutions.