Phonetically , consonants are most easily described in terms of their articulation because the organs involved and the points at which they make contact with other organs of speech are easily observable ; their articulation is accompanied by a clearly felt obstruction or contact made by the organs of speech involved consonants may be produced with or without voice ( vocal fold vibration ) ; consonants have a marginal position in the syllable , no syllabic function ( i.e. a syllable in English does not require a consonant ).

Consonants are speech sounds which are produced under noticeable stricture in the air stream caused by contact made between articulators in the oral cavity (e.g. the tip of the tongue making contact with the upper front teeth or the lips closing, thus forming a brief hindrance in the air stream). But there is also another characteristic distinction to be drawn based on the free or obstructed flow of the air stream, this time between two different types of consonants. The vocal cords may either allow the air to pass through freely or hinder its flow by loosely closing the opening of the glottis such that the vocal folds will vibrate as air passes through them. If the air is hindered, the vocal cords vibrate - a sound thus produced is a voiced sound. If the air flows freely, the sound is unvoiced (voiceless). The set of consonants is thus divided into a set of voiced consonants and a complementary set of consonants which are voiceless. Such differences occur for example between the initial sounds of these words (the voiceless sound occurring first in the table):

voiceless voiced
put but
ton done
Sue zoo

One can feel the difference by placing one's fingers on the pharynx and pronouncing the first sound of each pair of words.

In the description of the consonants of a language based on articulatory features, three chief characteristics are essential. The first feature involves the voiced / voiceless distinction: every sound is either one or the other . Secondly, one must refer to the place of articulation; that is, the place and organ (articulator) participating in the production of the sound. In the last paragraph we mentioned the glottis, the opening between the vocal cords. If the sound is formed here, it is referred to as a glottal sound. Two English sounds are formed at the glottis: the initial sound in 'his' and in some regional variants a glottal sound as the 't' in 'bottle' is formed by stopping the air flow at the glottis rather than stopping it at the alveolar ridge as in 'ten'. The third important characteristic involves the manner of articulation; that is, how the air flow is interrupted or channeled as it flows forth from the larynx.

Descriptive features of consonants: voicing
place of articulation
manner of articulation

Table 1-1: Overview of articulatory features of English consonants