During World War II, work at the Bell Telephone Laboratories (which invented the spectrograph) greatly facilitated the systematic study of the spectral properties of periodic and aperiodic speech sounds, vocal tract resonances and vowel formants, voice quality, prosody, etc.
Integrated linear prediction residuals (ILPR) was an effective feature proposed by T V Ananthapadmanabha in 1995, which closely approximates the voice source signal.
Lord Rayleigh was among the first to recognize that the new electric theory could be used in acoustics, but it was not until 1941 that the circuit model was effectively used, in a book by Chiba and Kajiyama called "The Vowel: Its Nature and Structure".
In 1952, Roman Jakobson, Gunnar Fant, and Morris Halle wrote "Preliminaries to Speech Analysis", a seminal work tying acoustic phonetics and phonological theory together.
Other important framers of the field include Kenneth N. Stevens who wrote "Acoustic Phonetics", Osamu Fujimura, and Peter Ladefoged.