Editing Audio system measurements (section)

== Unquantifiable? ==
{{missing information|section|newer objective metrics designed to match subjective [[sound quality]], including [[PEAQ]] (1998) and ViSQOL (Google, 2015)|date=August 2023}}
Many audio components are tested for performance using objective and quantifiable measurements, e.g., THD, dynamic range and frequency response. Some take the view that objective measurements are useful and often relate well to subjective performance, i.e., the sound quality as experienced by the listener.<ref>Aczel, Peter, [http://www.theaudiocritic.com/back_issues/The_Audio_Critic_29_r.pdf "Audio Critic"] {{webarchive |url=https://web.archive.org/web/20070928214133/http://www.theaudiocritic.com/back_issues/The_Audio_Critic_29_r.pdf |date=28 September 2007 }}, ''Issue No. 29'', ''Our Last Hip-Boots Column'', page 5-6, Summer 2003</ref> Floyd Toole has extensively [[Loudspeaker acoustics|evaluated loudspeakers]] in [[acoustical engineering]] research.<ref>{{Cite web|url=http://www.torontoaes.org/Seminar2008/bios/guests/Floyd_Toole.html|title=Floyd Toole|date=26 October 2008}}</ref><ref>{{Cite web|url=http://www.cirmmt.org/activities/distinguished-lectures/toole|title = Floyd Toole, consultant to Harman International, USA: Sound reproduction – art and science/Opinions and facts — CIRMMT}}</ref> In a [[peer reviewed]] [[scientific journal]], Toole has presented findings that subjects have a range of abilities to distinguish good loudspeakers from bad, and that [[blind experiment|blind]] listening tests are more reliable than sighted tests. He found that subjects can more accurately perceive differences in speaker quality during [[monaural]] playback though a single loudspeaker, whereas subjective perception of [[stereophonic sound]] is more influenced by room effects.<ref>{{cite web |url=http://www.almainternational.org/yahoo_site_admin/assets/docs/Pt_1_ASA_Providence_2014_with_notes_6-14.154134559.pdf |title=Archived copy |website=www.almainternational.org |access-date=12 January 2022 |archive-url=https://web.archive.org/web/20160717035403/http://www.almainternational.org/yahoo_site_admin/assets/docs/Pt_1_ASA_Providence_2014_with_notes_6-14.154134559.pdf |archive-date=17 July 2016 |url-status=dead}}</ref> One of Toole's papers showed that objective measurements of loudspeaker performance match subjective evaluations in listening tests.<ref>Toole, Floyd, [https://web.archive.org/web/20030403060501/http://www.harman.com/wp/pdf/AudioScience.pdf "Audio – Science in the Service of Art"], Harman International Industries Inc., 24 October 2004</ref>

Some argue that because human hearing and perception are not fully understood, listener experience should be valued above everything else. This is often encountered in the world of [[home audio]] publications.<ref name=Black1988>{{cite magazine |first=Richard |last=Black |title=A 'subjectivist' writes...A matter of timing: 'Subjectivism' defended |date=December 1988 |magazine=Hi-Fi News & Record Review |page=33}}</ref> The usefulness of blind listening tests and common objective performance measurements, e.g., THD, are questioned.<ref>Harley, Robert, [http://www.stereophile.com/asweseeit/491awsi/ "Were Those Ears So Golden? DCC and PASC"] {{webarchive |url=https://web.archive.org/web/20090122034000/http://www.stereophile.com/asweseeit/491awsi/ |date=22 January 2009 }}, ''Stereophile'', ''As We See It'', April 1991.</ref> For instance, crossover distortion at a given THD is much more audible than clipping distortion at the same THD, since the harmonics produced are at higher frequencies.  This does not imply that the defect is somehow unquantifiable or unmeasurable; just that a single THD number is inadequate to specify it and must be interpreted with care.  Taking THD measurements at different output levels would expose whether the distortion is clipping (which increases with level) or crossover (which decreases with level).

Whichever the view, some measurements have been historically favoured. For example, THD is an average of a number of harmonics equally weighted, even though research{{citation needed|date=January 2023}} identifies that lower order harmonics are harder to hear at the same level, compared with higher-order ones. In addition, even-order harmonics are said to be generally harder to hear than odd order. A number of formulas that attempt to correlate THD with actual audibility have been published, however, none have gained mainstream use.{{citation needed|date=June 2011}}

The mass market consumer magazine ''[[Stereophile]]'' promotes the claim that home audio enthusiasts prefer sighted tests than blind tests.<ref>Harley, Robert, [http://stereophile.com/asweseeit/182/index2.html "Deeper Meanings"], ''Stereophile'', ''As We See It'', July 1990.</ref><ref>Atkinson, John, [http://stereophile.com/asweseeit/705awsi/ "Blind Tests & Bus Stops"], ''Stereophile'', ''As We See It'', July 2005.</ref>