Editing Formant (section)

==History==
From an acoustic point of view, phonetics had a serious problem with the idea that the effective length of vocal tract changed vowels.<ref>{{Cite book |last=Hermann |first=Ludimar |title=Phonophotographische Untersuchungen |year=1894 |edition=5th |language=de |trans-title=Phonophotographical Studies}}</ref> Indeed, when the length of the vocal tract changes, all the acoustic resonators formed by mouth cavities are scaled, and so are their resonance frequencies. Therefore, it was unclear how vowels could depend on frequencies when talkers with different vocal tract lengths, for instance [[Bass (voice type)|bass]] and [[soprano]] singers, can produce sounds that are perceived as belonging to the same phonetic category. There had to be some way to normalize the spectral information underpinning the vowel identity. [[Ludimar Hermann|Hermann]] suggested a solution to this problem in 1894, coining the term “formant”. A vowel, according to him, is a special acoustic phenomenon, depending on the intermittent production of a special partial, or “formant”, or “characteristique” feature. The frequency of the “formant” may vary a little without altering the character of the vowel. For “long e” (''ee'' or ''iy'') for example, the lowest-frequency “formant” may vary from 350 to 440&nbsp;Hz even in the same person.<ref name="McKendrick">McKendrick, J. G. (1903). Experimental phonetics. In Annual report of the board of regents of the Smithsonian institution for the year ending June 30, 1902 (pp. 241–259). Smithsonian Institution.</ref>