Have you ever wondered how difficult it is to find a truly quiet place? At home, household appliances are noisy. At work, computers and air conditioners hum, and coffee machines gurgle and much more. If you work in manufacturing, it is not unusual that the noise level is so high that you have to use hearing protection. In the car, there is road and engine noise, and even far out in the woods, one is surrounded by unwanted noise from roads, industries and communities.
“Noise pollution” implies that environmental sounds experienced by the individual is disruptive. It can lead to a number of health problems.
Hearing loss is an obvious consequence of excessive noise levels but noise can also cause sleep disorders, high blood pressure and mental illness. One in five Europeans is exposed to noise exceeding 55 dB during the night, a level that can cause elevated blood pressure and heart disease.
The EU takes noise very seriously and is working with policies, strategies, legislation, and monitoring and research to reduce noise interference in society. The WHO (World Health Organization) has recently published guidelines for noise at night and states that outdoor noise exposure should not exceed 40 dB. The automotive and aerospace industries, and many others in the industrial community therefore face significant challenges.
Swedish company Creo Dynamics works to reduce noise levels inside and outside of buses, planes, trains and automobiles.
The right noise in moderation
“We work with noise sources in traditional vehicles, but we see many interesting challenges in reducing noise and vibration in hybrid vehicles and electric cars,” says Gustav Kristiansson, CEO of Creo Dynamics.
“To reduce noise is an obvious goal for us, but an electric car can actually be too quiet and pose a danger to pedestrians who do not hear as it approaches. To achieve the right kind of noise and vibration characteristics, we are working to reduce the annoying noise, and to enhance sound that contributes to the product’s positive attributes, giving the right information to the driver and the environment.”
With its roots in the aviation industry and with expertise in research, product development and consulting, Creo Dynamics creates conditions for the development of innovative products.
“We are a bunch of scientists and engineers who work with everything from individual components to complete products and systems. Our business concept is based on the combination of research, testing and practical experience,” says Kristiansson.
To support product development, Creo Dynamics has a laboratory for analysis, testing and simulation. This would include noise and vibration measurements of vehicles, household appliances, handheld tools and other things.
Comfortable noise levels in the car
“We work a lot with active noise control in vehicles and by switching off the sound waves of opposite sound waves, and the result is “The sounds of silence.”
“One example is road noise that is perceived as the most annoying noise inside the car, with frequencies up to 300 Hz. For this, we need active noise control,” says Kristiansson. “The noise is caused by the tire interaction with the road surface. Since the road surface can consist of many different surfaces and be uneven, it is important to capture the sound characteristics as accurately as possible. It is then possible to convey this information to the audio system in the car.”
“Microphones inside the car do not react quickly enough. It takes a few milliseconds for the tire vibrations to transfer into the car’s structure inside the car,” says Kristiansson.
The systems available today use a large number of accelerometers that are attached to the suspension system in the chassis. Such systems capture the vibrations and match the sound and reduce road noise. A system with many accelerometers is expensive and complicated to use in normal cars.
“Our goal is to use a single sensor to register the vibrations that cause noise. We believe that our software is a cheaper solution than expensive accelerometers. Our software is scalable, which may open the market for active noise control even for cars,”says Kristiansson. “At the moment we are working with another company to refine the signal from the sensor to fully get the information needed for our system.”
Test of lightweight composite material
The choice of materials is an important factor when businesses adapt their products to environmental standards. For airplanes, wind turbines, cars and household appliances low weight is of particular interest to many developers.
Glass and carbon fiber offer low weight and provide durability and strength. When such materials are used as structural elements in vehicle construction for example, it becomes particularly important to test the properties without destroying the product.
Here is where Creo Dynamics use their skills in acoustics and noise in order to develop non-destructive testing methods. Keeping the acoustic emissions at a low level in the use of lightweight and durable materials provides many challenges for product developers. There are many opportunities in the development of both new technologies and testing methods.
Reduced fuel consumption
In addition to experimental and applied acoustics, Creo Dynamics works with aerodynamics, thermodynamics and fluid dynamics, and one of the aims is to achieve reduced fuel consumption in different vehicles. One concept that is being developed is based on millimeter-sized “wings” that are placed on car bumpers. “We believe that fuel consumption can be reduced by several percent, and the technology is patent pending by Creo Dynamics,” says Kristiansson.
The article was published in December 2013