The vowel space illustration provides a graphical method of showing where a speech sound, such as a vowel, is located in both "acoustic" and "articulatory" space. The illustration shows an acoustic vowel space based on the first two formants for vowels (formants are the bands of energy that correspond to the resonances of the vocal tract for particular shapes). The vertical axis represents the frequency of the first formant (F1). The horizontal axis shows the frequency gap between the first two formants (F2-F1).
This 2-dimensional representation corresponds, to a certain degree, to tongue body position, with indications of high vs. low and front vs. back positions -- an articulatory space.
Additional information is available for those vowels that have been marked in this space. A short snippet of synthesized sound for each vowel is provided. In addition, the steps involved in the synthesis process for each vowel can be shown.