Editing Shepard tone (section)

===Tritone paradox===
{{main|Tritone paradox}}
A sequentially played pair of Shepard tones separated by an [[interval (music)|interval]] of a [[tritone]] (half an octave) produces the [[tritone paradox]]. Shepard had predicted that the two tones would constitute a bistable figure, the auditory equivalent of the [[Necker cube]], that could be heard ascending or descending, but never both at the same time.<ref name="Shepard1964" />
[[File:Paradoxa del tríton.wav|thumb|Sequence of Shepard tones producing the tritone paradox]]
In 1986, [[Diana Deutsch]] discovered that the perception of which tone was higher depended on the absolute frequencies involved and that an individual would usually hear the same pitch as the highest (this is determined by the absolute pitch of the notes).<ref name="Deutsch1986">{{cite journal|last=Deutsch|first=Diana|year=1986|title=A musical paradox|url=http://philomel.com/pdf/MP-1986_3_275-280.pdf|journal=Music Perception|volume=3|issue=3|pages=275–280|doi=10.2307/40285337|jstor=40285337}}</ref> Interestingly, different listeners may perceive the same pattern as being either ascending or descending, depending on the language or dialect of the listener (Deutsch, Henthorn, and Dolson found that native speakers of [[Vietnamese language|Vietnamese]], a [[Tone (linguistics)|tonal]] language, heard the tritone paradox differently from Californians who were native speakers of English).<ref name="Deutsch1992">{{Cite journal 
| last1 = Deutsch | first1 = D. 
| title = Some New Pitch Paradoxes and their Implications 
| doi = 10.1098/rstb.1992.0073 
| journal = Philosophical Transactions of the Royal Society B: Biological Sciences 
| volume = 336 
| issue = 1278 
| pages = 391–397 
| year = 1992 
| pmid = 1354379 
| bibcode = 1992RSPTB.336..391D 
}}</ref><ref>{{Cite journal|last1=Deutsch|first1=Diana|last2=Henthorn|first2=Trevor|last3=Dolson|first3=Mark|date=2004|title=Speech Patterns Heard Early in Life Influence Later Perception of the Tritone Paradox|url=http://dx.doi.org/10.1525/mp.2004.21.3.357|journal=Music Perception|volume=21|issue=3|pages=357–372|doi=10.1525/mp.2004.21.3.357|issn=0730-7829}}</ref>