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:
“Few, if any, creatures are equally active all night.”
—Henry David Thoreau (1817–1862)
“...if you are to gain any great amount of good from the world, you must attain a passive condition of mind. ...it is never to be forgotten that it is the rest of the world and not you that holds the great share of the world’s wealth, and that you must allow yourself to be acted upon by the world, if you would become a sharer in the gain of all the ages to your own infinite advantage.”
—Anna C. Brackett (1836–1911)
“You have to make more noise than anybody else, you have to make yourself more obtrusive than anybody else, you have to fill all the papers more than anybody else, in fact you have to be there all the time and see that they do not snow you under, if you are really going to get your reform realized.”
—Emmeline Pankhurst (1858–1928)
“Not being able to control events, I control myself; and I adapt myself to them, if they do not adapt themselves to me.”
—Michel de Montaigne (1533–1592)