There are two major classes of sounds traditionally distinguished by phoneticians in any language. They are termed consonants and vowels. The distinction is based mainly on auditory effect. Consonants are known to have voice and noise combined, while vowels are sounds consisting of voice only. From the articulatory point of view the difference is due to the work of speech organs. In case of vowels no obstruction is made. In case of consonants various obstructions are made. So consonants are characterized by so-called close articulation that is by a complete, partial or intermittent blockage of the air-passage by an organ or organs. The closure is formed in such a way that the air-stream is blocked or hindered or otherwise gives rise to audible friction. As a result consonants are sounds which have noise as their indispensable and most defining characteristic. On the articulatory level, each consonant may be identified by stating two general facts about it:
1) what sort of articulatory posture it is formed by; 2) whereabout in the mouth (or pharynx) it is produced. Besides these major characteristics the particular quality of a consonant may depend on a lot of other factors, that is by what articulatory organ (or organs) an obstruction is made, how vocal cords work at the moment of production, what cavity is used as a resonator, what is the force of articulatory effect and many others. According to V.A.Vassilyev, primary importance should be given to the type of obstruction and the manner of production of noise. On this ground, he distinguishes two large classes of consonants: a) occlusive, in the production of which a complete obstruction is formed; b) constrictive, in the production of which an incomplete obstruction is formed. The phonological relevance of this feature could be exampled in the following oppositions: [ti:] – [si:] – tea – sea (occlusive – constructive) [si:d] – [si:z] – seed – seas (occlusive – constructive) [pul] – [ful] – pull – full (occlusive – constructive) [bзut] – [vзut] – boat – vote (occlusive – constructive) Each of two classes is subdivided into noise consonants and sonorants. The division is based on the factor of prevailing either noise or tone component in the auditory characteristic of a sound. In their turn noise consonants are divided into plosive consonants (or stops) and affricates.
Another point of is that the first and basic principle of classification should be the degree noise. Such consideration leads to dividing English consonants into two general kinds: A — noise consonants
B — sonorants
in production of sonorants the air passage between the two organs of speech is fairly wide, that is much wider than in the production of noise consonants. As a result, the auditory effect is tone, not noise - [r], [j], [w], for example. They are also characterized by sharply defined formant structure and the total energy of most of them is very high.
The phonological relevance of the degree of noise could be proved by the following oppositions:
[beik] — [meik] bake — make (noise consonant — sonorant) [vi:l – [wi:l] veal — wheel (noise consonant — sonorant) The place of articulation is determined by the active organ of speech against the point of articulation. According to this principle the English consonants are classed into: 1) labial, 2) lingual, 3) glottal. The class of labial consonants is subdivided into: a) bilabial; b) labio-dental; and among the class of lingual consonants, three subclasses are distinguished; they are: a) forelingual, b) mediolngual and c) backlingual. Also, American phoneticians specifically distinguish consonants made in dental, interdental, alveolar, palatal, alveopalatal, velar, uvular, pharyngeal, glottal positions. Another sound property is voiced — voiceless characteristic which depends on the work of the vocal cords. [p, b], [t, d], [k, g], [s, z], [f, v], [∫, ],''[t∫, d ]. All voiced consonants are weak (lenis) and all voiceless consonants are strong (fortis). Thus it may be said that the oppositions [p — b], [t — d], [k — g], [f — v], [s — z], [∫— ], [t∫ — d ] are primarily based on energy difference, that is on fortis — lenis articulation, which are their phonologically relevant features. It is for this reason that such characteristics as voiceless — voiced have given place to "fortis" — "lenis" terms. There is one more articulatory characteristic which is usually included into the set of principles, on the basis of which the English consonants are classified, that is the position of the soft palate. According to this principle, consonants can be oral and nasal. There are relatively few consonantal types in English, which require the lowered position of the soft palate. They are the nasal occlusive sonorants [m], [n] and[ŋ]. They differ from oral plosives in that the soft palate is lowered allowing the escape of air into the nasal cavity.
Fricatives. Fricatives are consonants produced with a continuous airflow through the mouth. English has voiceless and voiced labiodental fricatives at the beginning of the words fat and vat, interdental fricatives heard word initially in words thin and those, alveolar fricatives in sing and zip, and a voiceless alveopalatal fricative in ship. The voiced alveopalatal is rare in English; it is in words like azure, pleasure, and rouge. The voiceless glottal fricative of English is heard in words hotel, hat. Affricates.When a stop articulation is released, the tongue moves rapidly away from the point of articulation. Some noncontinuant consonants show a slow release of the closure; these sounds are called affricates. English has two affricates. They are hears word initially in church and jump.