formanten

Formanten are the resonant frequencies of the vocal tract that shape the spectrum of most speech sounds. They appear as peaks in the frequency spectrum and arise from the vocal tract acting as a series of resonators when it is shaped by articulation. The major formants, typically labeled F1, F2, and F3, reflect how the vocal tract is configured by the tongue, lips, jaw, and glottis during speech. The formants determine vowel quality and contribute to the perceptual distinctions among vowel sounds.

The relationship between formants and articulation is systematic: F1 is inversely related to vowel height (higher vowels tend to have a lower F1), while F2 is related to tongue frontness (front vowels generally have higher F2 values). F3 carries additional, though less systematic, information about vowel quality and other articulatory features. Because the vocal tract length and shape vary among speakers and languages, formant frequencies can differ substantially across individuals, dialects, and age groups.

Formants are typically estimated from recorded speech using spectral analysis methods such as spectrograms or linear predictive coding (LPC). They are central to vowel classification in phonetics and linguistics, and they underpin many practical applications in speech technology, including speech synthesis, automatic speech recognition, and speaker identification.

Historically, the concept traces back to the study of vocal tract resonances in the 19th century, with formal development in the 20th century. Formant synthesis, a key milestone, was advanced by Gunnar Fant in the 1950s–1960s, demonstrating how changing formant patterns could produce intelligible speech without recorded samples.