Term: Noise, digital audio
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Term: Noise, digital audio
- Definition:
- Noise has a number of meanings in terms of sound. This definition pertains to the measurement of noise in digitizing equipment, as when the International Association of Sound and Audiovisual Archives (IASA) specifies pass-fail values for the measurement of THD plus noise (THD+N). Different methods are used by different organizations to measure the type of noise referenced in this expression. A-weighting is often used in the United States, employing a family of curves defined in the international standard IEC 61672:2003 and various national standards relating to the measurement of sound level, as opposed to actual sound intensity. One of the pass-fail values suggested in the IASA specification is for readings made using the A-weighted method; the other value suggested is for unweighted noise. Meanwhile, in Europe and many other parts of the world, audio engineers often use the ITU-R 468 noise weighting, which was developed in the 1960s based on research by the BBC and other organizations. This research showed that human ears respond differently to random noise, and the equal-loudness curves on which the A, B, and C weightings were based are really only valid for pure single tones.
- Category:
- Audio
- Resource:
- A-weighting (Wikipedia article)
http://en.wikipedia.org/wiki/A-weighting - ITU-R 468 Noise Weighting (Wikipedia article)
http://en.wikipedia.org/wiki/ITU-R_468_noise_weighting - Guidelines on the Production and Preservation of Digital Objects, August 2004 (IASA TC 04)
http://www.iasa-web.org/special_publications.asp - See also:
- Aliasing; Artifact (defect); Dither; Distortion; Noise; Signal to noise ratio