Near-Field Active Noise Suppression
A multi-channel adaptive control algorithm with system hardware placed in the acoustic near-field for the active minimization of primarily tonal noise from axial flow fans.
The current invention consists of a design for an active control system that will significantly reduce the tonal component of the radiated cooling fan noise on a global scale, both quieting the overall noise spectrum and reducing its most annoying component. The system has been researched and designed so that it will be both compact and inexpensive, thereby providing a practical means of reducing noise without significantly affecting the price of the product.
Many electronic devices require external cooling to prevent overheating and thermal damage to components. This is usually accomplished by one or more axial cooling fans that, in turn, produce an undesired result in that they become a source of noise. This noise radiation often increases background noise levels, interfering with communication, disrupting concentration, or simply causing annoyance. The type and amount of noise produced by a fan varies depends on both the application in which it is used as well as the number of blades and rotational rate. Obstructions to flow near the inlet or outlet (also called the exhaust) of the fan significantly increase the amount of noise radiated, especially the tonal noise component, to which the human ear is particularly sensitive. Because these flow obstructions cannot be eliminated in most applications, a noise reduction method is then needed.
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