Editing Distortion (section)

===Harmonic distortion===
Harmonic distortion adds [[overtone]]s that are [[Integer|whole number]] multiples of a sound wave's frequencies.<ref>{{Cite book
  | last = Moscal
  | first = Tony
  | title = Sound Check: The Basics of Sound and Sound Systems
  | publisher = Hal Leonard 
  | year = 1994
  | page = 55
  | url = https://books.google.com/books?id=_omgNjqf7GAC&q=harmonic+distortion+whole+integer&pg=PA55
  | isbn = 9780793535590}}</ref> Nonlinearities that give rise to amplitude distortion in audio systems are most often measured in terms of the [[harmonic]]s (overtones) added to a pure [[sinewave]] fed to the system. Harmonic distortion may be expressed in terms of the relative strength of individual components, in [[decibel]]s, or the [[root mean square]] of all harmonic components: [[Total harmonic distortion]] (THD), as a percentage. The level at which harmonic distortion becomes  audible depends on the exact nature of the distortion.  Different types of distortion (like [[crossover distortion]]) are more audible than others (like [[soft clipping]]) even if the THD measurements are identical.  Harmonic distortion in [[radio frequency]] applications is rarely expressed as THD.