Active Vs. Passive Noise Control
Noise control is an active or passive means of reducing sound emissions, often incentivised by personal comfort, environmental considerations or legal compliance. Active noise control is sound reduction that utilizes a power source. Passive noise control is sound reduction by noise-isolating materials such as insulation, sound-absorbing tiles, or a muffler rather than a power source.
Active noise canceling is best suited for low frequencies. For higher frequencies, the spacing requirements for free space and zone of silence techniques become prohibitive. In acoustic cavity and duct based systems, the number of modes grows rapidly with increasing frequency, which quickly makes active noise control techniques unmanageable. Passive treatments become more effective at higher frequencies and often provide an adequate solution without the need for active control.
Advantages of active noise control
- More effective at low frequencies.
- Less bulky.
- Able to block noise selectively.
Advantages of passive noise control
- More effective above 2000 Hz
- Does not require a power source
- Generally cheaper to implement
Read more about this topic: Active Noise Control
Famous quotes containing the words active, passive, noise and/or control:
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—Gore Vidal (b. 1925)
“It is my conviction that in general women are more snobbish and class conscious than men and that these ignoble traits are a product of men’s attitude toward women and women’s passive acceptance of this attitude.”
—Mary Barnett Gilson (1877–?)
“Let there be no noise made, my gentle friends,
Unless some dull and favorable hand
Will whisper music to my weary spirit.”
—William Shakespeare (1564–1616)
“Religion differs from magic in that it is not concerned with control or manipulation of the powers confronted. Rather it means submission to, trust in, and adoration of, what is apprehended as the divine nature of ultimate reality.”
—Joachim Wach (1898–1955)