formant (n.) (F)

A term in ACOUSTIC PHONETICS of particular value in the classification of VOWELS and vowel-like sounds, and of TRANSITIONAL features between vowels and adjacent sounds. A formant is a concentration of acoustic energy, reflecting the way air from the lungs vibrates in the VOCAL TRACT, as it changes its shape. For any vowel, the air vibrates at many different frequencies all at once, and the most dominant frequencies combine to produce the distinctive vowel QUALITIES. Each dominant band of frequencies constitutes a formant, which shows up clearly in a record produced by a sound SPECTROGRAPH as a thick black line. Three main formants provide the basis of vowel description: the first formant (F1) is the lowest, and the second and third formants (F2, F3) are respectively higher. Other formants are less significant for linguistic analysis. The formants can be related to the ARTICULATORY DESCRIPTIONS of vowels, as represented, say, by the CARDINAL VOWEL diagram. The first formant, for example, decreases in its frequency as one moves from low to high (e.g. sat ⇒ set ⇒ seat). In the case of CONSONANTS, similar correlations can be established: for example, in the transition from VELAR consonants, the second and third formants come very close together.