Active Noise Control Products

Active noise control products use electro-acoustical sound field modification or cancellation to attenuate or eliminate unwanted sound. By contrast, passive noise control products use materials to absorb sound. Active noise control products include controllers, sensors, actuators, and other electro-acoustical products for limiting or canceling noise or vibration. In a typical active noise control system, sensors are used to detect unwanted sound when it occurs. A controller and speaker are then used to create a sound field that is a twin of the unwanted sound, but inverted, so that it is a mirror image of the sound to be eliminated an anti-sound.

Active noise control products treat unwanted sound as a wave with peaks and troughs of sound pressure. The anti-sound created by active noise control products is an inverse wave. In other words, the troughs of the unwanted sound match the peaks of the anti-sound. The result it that, when the two sounds meet, the peaks and troughs in the sound and the anti-sound cancel each other out, causing the unwanted sound to disappear. The key to active noise control is that, for optimum performance, the unwanted sound and the anti-sound must be matched closely both in both space and time. This is why the sensor and controller parts of an active noise control system are so important and why the particular situation must be carefully studied before an active noise control system is employed.

Providers of active noise control products are located across the United States and around the world. Some companies manufacture products that are suitable for active noise control or active noise reduction. Other companies provide products that are designed for vibration control. Many active noise control products feature certifications and approvals.

• Active Sound and Vibration Control: Theory and Applications
  Active Sound and Vibration Control: Theory and Applications There has been considerable effort devoted to the development and realization of methodologies for control of sound and vibration. This...
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