Summary

Speech sounds are commonly divided into two main categories in human languages: vowels, such as ‘e’, ‘a’, ‘o’, and consonants, such as ‘k’, ‘n’, ‘s’. This division is made on the basis of both phonetic and phonological principles, which is useful from a general linguistic point of view but problematic for detailed description and analysis. The main differences between vowels and consonants are that (1) vowels are sounds produced with an open airway between the larynx and the lips, at least along the midline, whereas consonants are produced with a stricture or closure somewhere along it; and (2) that vowels tend to be syllabic in languages, meaning that they embody a sonorous peak in a syllable, whereas only some kinds of consonants tend to be syllabic. There are two main physical components needed to produce a vowel: a sound source, typically a tone produced by vocal fold vibration at the larynx, and a resonator, typically the upper airways. When the tone resonates in the upper airways, it gets a specific quality of sound, perceived and interpreted as a vowel quality, for example, ‘e’ or ‘a’. Which vowel quality is produced is determined by the shape of the inner space of the throat and mouth, the vocal tract shape, created by the speaker’s configuration of the articulators, which include the lips, tongue, jaw, hard and soft palate, pharynx, and larynx. Which vowel is perceived is determined by the auditory and visual input as well as by the listener’s expectations and language experience. Diachronic and synchronic studies on vowel typology show main trends in the vowel inventories in the worlds’ languages, which can be associated with human phonetic aptitude.