Editing Active noise control (section)

== Active vis-à-vis passive noise control ==
''Noise control'' is an active or passive means of reducing sound emissions, often for personal comfort, environmental considerations, or legal compliance. ''Active'' noise control is sound reduction using 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 nodes 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.<ref>{{cite web| title=Active Noise Control|website=medialab|date= December 2005| url=http://www.medialab.ch/archiv/pdf_studien_diplomarbeiten/da05/da2005-104_ActiveNoiseControl.pdf| archive-url=https://web.archive.org/web/20120426050529/http://www.medialab.ch/archiv/pdf_studien_diplomarbeiten/da05/da2005-104_ActiveNoiseControl.pdf| url-status=dead|archive-date=April 26, 2012 }}</ref>