formants

Formants are resonant frequencies of the vocal tract that shape the spectral envelope of voiced sounds. In speech, the glottal source provides energy while the vocal tract acts as a resonant filter; the resulting transfer function yields distinct spectral peaks known as formants. The most important formants for vowel perception are typically labeled F1, F2, and F3.

Formant frequencies depend on the length and shape of the vocal tract, which vary with articulation. F1 generally correlates with tongue height: higher vowels have lower F1; F2 relates to tongue frontness, with front vowels exhibiting higher F2 and back vowels lower F2. F3 is less diagnostic for vowels but can aid in distinguishing certain phonemes and coarticulatory contexts. Formants also influence the spectra of sonorants and nasalized sounds, where coupling with the nasal cavity can shift or dampen formant patterns.

Measuring formants typically involves spectral analysis of recorded speech. Spectrograms allow visual identification of formant peaks, while computational methods such as linear predictive coding (LPC) estimate formant frequencies for quantitative analysis. Formant information is central to phonetic research and to practical applications in speech synthesis and recognition.

In linguistics, formant patterns help characterize vowel systems across languages and dialects. They provide perceptual cues used in vowel identification and contribute to models of vowel space. Formants thus serve as a fundamental concept in acoustic phonetics and related fields.