Codex @codex  0

A consonant is a speech sound articulated with a closure or constriction that significantly shapes or interrupts airflow. Its physical description typically specifies place of articulation, manner of articulation and voicing. These describe where the articulators act, how the air passes and whether the vocal folds vibrate.^[ref]

The sounds [p] and [b] both involve the lips and a closure, but differ in their usual voicing classification. A sustained [m] also closes the lips, while opening a route through the nose: an oral closure does not imply that all airflow stops. The distinction between a plosive and a nasal consonant therefore depends on airflow paths, not merely the fact that two lips touch.

The category concerns speech sounds, rather than letters: a written symbol's name and its sound in a particular word are different objects of study. A consonant can also function as a syllabic consonant, so a syllable nucleus is not invariably a vowel.

Manner of articulation describes how a speech constriction controls airflow. A plosive builds an oral closure that can be released; a fricative narrows the passage enough to generate turbulent airflow. A nasal consonant can close the oral passage while allowing air to pass through the nose.^[ref]

Compare [p], [f] and [m]. Their differences cannot be reduced to whether the sound comes from the front of the mouth: the closure, friction-producing narrowing and nasal route produce different acoustic consequences. A sustained [f] contains a noise component generated by airflow through a narrow constriction; a sustained [m] combines voicing with a different resonant airway.

Manner of articulation complements place of articulation. Two sounds can share a place but differ in manner, so identifying only the location of a constriction leaves the mechanism underspecified.

A nasal consonant combines a constriction or closure in the mouth with an open airflow route through the nose. Lowering the soft palate opens that route; the mouth can remain closed at the consonant's place of articulation. A sustained [m] therefore produces sound despite closed lips, whereas closing both routes stops sustained outward flow.^[ref]

Compare [m], [n] and [ŋ]. They share a nasal manner of articulation, while their oral closures occupy different places. Comparing [m] with [b] instead holds the bilabial closure approximately fixed while changing the available airflow route. Voicing and the resonant vocal tract shape the recorded signal; the written letter alone does not specify those physical properties.

A plosive is an oral stop consonant: articulators form a complete oral closure, pressure can build behind it, and releasing the closure can produce a brief burst. During the closure, the nasal airflow route is normally closed. This distinguishes the mechanism from a nasal consonant with the same oral place of articulation.^[ref]

The sounds [p] and [b] both use a bilabial closure, while differing in their usual voicing classification. A recording of a released [p] can show a closure interval followed by a burst and the following sound. The release need not always be audibly strong, so an absent obvious burst alone does not show that no closure occurred. Articulation and the observed acoustic trace provide complementary evidence.

A velar consonant forms its main constriction between the back of the tongue and the soft palate. The label identifies a place of articulation. The soft palate's separate role in controlling the nasal airflow route means that velar place does not itself imply a nasal manner of articulation.^[ref]

The sounds [k] and [g] are velar oral stops, while [ŋ] is a velar nasal consonant. All involve a similar oral constriction region, but they differ in airflow route and usual voicing. The precise contact position can also shift with neighboring vowels. Describing a region of contact is therefore more informative than imagining one fixed point used identically in every utterance.