Acoustic Phonetics
A description of speech sounds in terms of the acoustic consequence of their production.
A study on the [see page 3, production of vowels] and the associated first and second Formants shows that that their a [see page 6, direct correlation] between these formants and the vowel quadrilateral. We can construct the vowel space as a graph listing the frequencies of the first and second formants and [see page 7, plot] where we expect different vowels to show up.
We can also plot [see page 11, graphs] for voiced/voiceless fricatives.