Formants are tract resonances conveying speech information

Evidence

The vocal tract from the glottis to the lips is about 17 cm in length for an adult male (Rabiner and Schafer, 1978), and about 14.5 cm for females (Klatt and Klatt, 1990). In the middle of the vocal tract, the tip of the soft palate called the velum opens or closes the sideway through the nasal tract to the nostrils. In normal production of speech this is open only for nasalized sounds. The effect of these two tracts is to determine the acoustic transfer function in such a way that the spectral properties of the radiating voice can convey speech information through a rich set of distinct sounds. From a signal processing point of view, the vocal and nasal tracts act as filters with controllable resonances that emphasize specific frequencies. These resonances are called formants, which are one of the most important cues in speech. The tracts may also create antiformants, dips in the spectrum; in other words, zeros in the transfer function. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 556

Categorization

Category: Factual Claims

• DEFINE: Defines formants and antiformants as controllable resonances and zeros of the vocal tract transfer function.
• XREF: Formant/filter model directly connects to source-filter theory and applications in speech synthesis and voice recognition.
• SEED: The 17 cm vs 14.5 cm vocal tract length difference, tied to male/female formant differences, could anchor a piece on how gender differences in voice are partly physical tube acoustics rather than just pitch.

Related

• Vocal tract length differs by sex and its resonances form speech formants. (similarity 0.94)
• Formants are standing-wave resonances of the vocal tract itself (similarity 0.84)
• Vocal tract length and larynx size determine sex-typical pitch and formants (similarity 0.83)
• Vowels are distinguished by formant frequencies controlled by tongue, jaw, and lips (similarity 0.82)
• The vocal tract actively amplifies speech rather than merely filtering it (similarity 0.81)
• Vocal tract shape determines voice timbre far more than vocal cords do (similarity 0.79)
• Higher formants above the third shape vocal identity and projection (similarity 0.78)
• Voice differences include formant and temporal cues beyond fundamental frequency (similarity 0.78)