In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Consonants are produced as air from the lungs is pushed through the glottis (the opening between the vocal cords) and out the mouth. They are classified according to voicing, aspiration, nasal/oral sounds, places of articulation and manners of articulation.

Any of the phonemes of a language that are pronounced with the vocal channel closed (occlusive or momentary or explosive consonants) or semi-closed (semiocclusive or affricate and constrictive or fricative or continuous consonants) and cannot make a syllable by themselves, as opposed to vowels, which can make a syllable by themselves and are pronounced with the vocal channel open.

Consonants constitute one of the two major classes into which the articulated sounds of a language are divided. The boundary between consonants and vowels is not rigid. In fact, when two vowels follow each other, there are two cases: either both retain their full value, or one of the two assumes the function of a consonant (in which case it is properly called a semiconsonant or semivowel), giving rise to a diphthong. In turn, liquid consonants (r, l) and nasal consonants (n, m) can become sonorous, assuming the office of vowels.

Consonants are classified as follows:

  • according to the presence or lack of vibration of the vocal cords, into sonorous and deaf;
  • according to the intensity of articulation, into strong, medium and weak (or even soft or lenient);
  • according to the place of articulation, into labial, dental, alveolar, cacuminal, palatal, velar, uvular, pharyngeal and laryngeal;
  • according to the mode of articulation, in occlusive, semiocclusive and constrictive;
  • according to the duration, in simple and geminated.