Editing Formant (section)

==Formant plots==
[[File:Catford formant plot.png|thumb|A plot of the average formants listed in the above chart]]
The first two formants are important in determining the quality of vowels, and are frequently said to correspond to the open/close (or low/high) and front/back dimensions (which have traditionally been associated with the shape and position of the [[tongue]]). Thus the first formant ''F''<sub>1</sub> has a higher frequency for an open or low vowel such as {{IPA|[a]}} and a lower frequency for a closed or high vowel such as {{IPA|[i]}} or {{IPA|[u]}}; and the second formant ''F''<sub>2</sub> has a higher frequency for a front vowel such as {{IPA|[i]}} and a lower frequency for a back vowel such as {{IPA|[u]}}.<ref>Ladefoged, Peter (2006) ''A Course in Phonetics (Fifth Edition)'', Boston, MA: Thomson Wadsworth, p. 188. {{ISBN|1-4130-2079-8}}</ref><ref>Ladefoged, Peter (2001) ''Vowels and Consonants: An Introduction to the Sounds of Language'', Maldern, MA: Blackwell, p. 40. {{ISBN|0-631-21412-7}}</ref>

Vowels will almost always have four or more distinguishable formants, and sometimes more than six. However, the first two formants are the most important in determining vowel quality and are often plotted against each other in vowel diagrams,<ref>Deterding, David (1997) 'The Formants of Monophthong Vowels in Standard Southern British English Pronunciation', ''Journal of the International Phonetic Association'', 27, pp. 47–55.</ref> though this simplification fails to capture some aspects of vowel quality such as rounding.<ref>Hayward, Katrina (2000) ''Experimental Phonetics'', Harlow, UK: Pearson, p. 149. {{ISBN|0-582-29137-2}}</ref>

Many writers have addressed the problem of finding an optimal alignment of the positions of vowels on formant plots with those on the conventional vowel quadrilateral. The pioneering work of Ladefoged<ref>{{cite book|last1=Ladefoged|first1=P.|title=Three Areas of Experimental Phonetics|date=1967|publisher=Oxford|page=87}}</ref> used the [[Mel scale]] because this scale was claimed to correspond more closely to the auditory scale of [[pitch (music)|pitch]] than to the acoustic measure of [[fundamental frequency]] expressed in Hertz. Two alternatives to the Mel scale are the [[Bark scale]] and the [[Equivalent rectangular bandwidth|ERB-rate scale]].<ref>{{cite book|last1=Hayward|first1=K.|title=Experimental Phonetics|date=2000|publisher=Longman|isbn=0-582-29137-2}}</ref> Another widely adopted strategy is plotting the difference between ''F''<sub>1</sub> and ''F''<sub>2</sub> rather than ''F''<sub>2</sub> on the horizontal axis.{{Citation needed|date=November 2021}}