In today’s generation of home appliances, product quietness is a “must have.”
Imagine a busy home with every small appliance going – the cacophony of the microwave heating, the grating sound of the vacuum cleaner, the range hood humming… Don’t forget the washer and dryer churning away in the mud room, too.
Appliance manufacturers are responding to customer demand for quieter, more energy efficient products. When discussing the sound attributes of their products, companies not only talk about how quiet they are but they also need to discuss sound quality. Active noise control combined with traditional passive treatment will insure that their new product will sound better, as well as be quieter, than either their old product or the competition’s product.
As a rule, people should be able to speak in normal conversational tones within a distance of two meters, or slightly over six feet. Low audio frequencies travel a longer distance, crossing almost any barrier. The most effective way to deal with low frequencies is by active means.
Now, imagine the same kitchen using Active Noise Control (ANC) technology. All you hear is the sizzle of the frying pan and the microwave bell telling you your lunch is heated.
Active Noise Control Reduction in Range Hoods – A Case Study
In range hoods, a blower is typically used to moves air through the system, which is the most significant source of noise. The European Union and many other jurisdictions are setting targets for quieter electrical equipment. Therefore, the development of products based on active noise control is becoming increasingly necessary.
As a typical air-moving device, the range hood possesses three noise sources:
- Air Inlet
- Air Outlet
These three noise sources differ in their noise levels, their spectra and in their characteristic paths (airborne or structure borne).
The first step in the results analysis is to grade the noise sources according to the absolute sound power and the noise reduction potential. While the noise level varies among the three sources, all must be “treated” as part of the solution.
The ANC components – speaker, microphone and Silentium S-Cube™, located inside the chimney hood – reduce the noise emitted from the inlet. The S-Cube is a low–cost, basic building block for implementing an active acoustics control solution for mass-produced products, significantly reducing broadband noise and vibration.
By detecting the unwanted noise with the reference microphone, the ANC system automatically generates the correct signal to send to the speaker, which will produce the anti-noise to cancel out the unwanted noise generated by the blower. In addition, since noise is no longer a factor, the silenced blower can work at a higher operating efficiency, increasing the effectiveness of the appliance and reducing its overall energy consumption.
As most appliances already have boards as critical components, Active Noise Control can simply become an additional chip. Once calibration is achieved, the error microphone can be replaced with an algorithm. The higher the production level, the lower the cost of creating a quieter appliance. When the time comes for consumers to make their purchase, they will opt to pay a little extra for a superior engineered product providing a quieter environment.