I have read that for front vowels, the cavity behind the lips (I think this must correspond to the space between the lips and the hump of the tongue) is F3, whereas for back vowels it is F2.

In that case, what dictates F3 for back vowels? Is it the space between the hump of the tongue and the pharanx, with the space between the hump of the tongue and the lips becoming F2 (because it is the smallest of the three spaces in this configuration)?

What does F4 correspond to, and does this vary depending on whether the vowel is front or back? Is there a fourth resonator / airspace somewhere?

Would a vowel with formants 335, 1515, 2680, 3350 Hz be considered a front vowel or a back vowel? By the criteria I have found it is between the two - so I am not sure what F2 - F4 represent. Specifically, in a vowel with approximately those formants, how can F3 be raised without also raising F2 (or how can F2 and F3 be pushed apart)?

  • There are not formal correspondences between the formants and the articulatory positions, even for F1 and F2. So don't bother yourself to know to which position F4 corresponds, because no one in the world has established such relation.
    – amegnunsen
    Commented Nov 19, 2018 at 15:42

1 Answer 1


I refer you to this answer about a similar question for F1, i..e "it's complicated". F3 is not well understood, although it plays a role in distinguishing American English r. F4 is an engineering mystery. You can manipulate F4 all you want, and it has little if any effect on vowel quality (whereas lowering F3 to something around 2100 Hz or less will have an rhoticizing effect). Fant's Acoustic Theory of Speech Production will lay out his theory of how formants arise.

  • I think F3 is important in the vowel I am looking at because a vowel that is within the range as regards F1&F2 is still not acceptable to native speakers. There could be other explanations but I'm not quite ready to rule out F3. I can lower it as in a rhoticized schwa but I need to raise it. Is it fruitful to look at different ways to produce the same F1&F2 (or F1/F2 ratio)? In the 2-tube model length can be adjusted at both ends and the boundary can also be moved, so it makes sense that there would be different ways to get the same F1/F2. I am not sure I know how to raise the glottis though.
    – user23078
    Commented Nov 19, 2018 at 22:56
  • I will try to get hold of Fant BTW
    – user23078
    Commented Nov 19, 2018 at 22:56
  • Are you doing source-filter synthesis in Praat?
    – user6726
    Commented Nov 19, 2018 at 23:15
  • I was wondering whether there was a tool like that out there and it turns out I already have it... so the answer is I wasn't but I will be as soon as I get to grips with it. Thanks.
    – user23078
    Commented Nov 20, 2018 at 8:20

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