Linguists make use of the speech apparatus just explained to classify and describe the sounds of speech. The stream of speech sound is cut up into segments according to the way the sound is produced. One basic classification is the distinction between vowels and consonants. Vowels are those segments of speech produced without any interruption or stoppage of the airstream e.g. [i], [u]. Passage of air is continuous and frictionless. Consonants on the other hand, are segments marked by interruption of airstream. When the interruption is complete a stop is produced as in [t], [d]. When it is incomplete and accompanied by friction a fricative is produced as in [s], [v]. The interruption may be in the form of various kinds of trills as in Scottish [r]. All vowels are produced with vibration of the vocal cords, but consonants may be produced with or without vibration.
The answers to the four questions in the preceding paragraphs can tell us how the consonants are produced and also help us us to classify or describe them.
1. Are the vocal cords vibrating? The answer to this question tells us whether the sound is voiced or voiceless.
2. What point of articulation is approached by the articulator? The answer gives the adjective in naming the consonant. For example, if the upper lip is approached by the lower lip, the sound is bilabial, e.g. [m, b]. If the uoper teeth are approached by the lower lip, the sound is labiodental, e.g. [f, v].
3. What is the manner of articulation? The answer supplies the noun in naming the consonant, e.g. stops, fricatives, affricates.
4. Is the air issuing through the mouth or nose? The answer tells us whether it is an oral or a nasal sound. This may be taken with (3) as another manner of articulation as it supplies another noun in the naming of consonants, i.e. nasal.
We will group the consonant sounds of English according to their manner of articulation in the following discussion.
Stops. The stops in English are [p, b, t, d, k, g]. Stops are produced by stopping the passage of the breath stream, with a build-up of pressure behind the closure and then releasing the breath. If the breath is stopped by the lips coming together, either a [p] or [b] is produced when the breath is released. These are bilabial stops; [p] is voiceless and [b] is voiced. The air may be stopped at the alveolar ridge by raising the tip of the tongue to produce the alveolar stops, voiceless [t] and voiced [d]. Farther back in the mouth the air may be stopped at the velum (soft palate) by raising the front of the tongue, thereby producing the velar stops, voiceless [k] and voiced [g].
Fricatives. There are ten fricatives in English, [f, v, θ, ð, s, z, ʃ, ʒ, r, h]. Fricatives are produced when the air stream is not completely stopped but pass through with friction or hissing sound. If the upper teeth (as the point of articulation) and the lower lip make the opening through which air passes with friction, the labiodental fricatives are produced, voiceless [f] and voiced [v]. If the tip of the tongue shapes an opening with the upper teeth, then the dental fricatives [θ] and [ð]result. [θ] is voiceless as in the beginning of thin and through. [ð] is voiced as in the beginning of then and though.
Six other fricatives are produced farther back in the mouth. In the first pair the tip of the tongue is raised close to the alveolar ridge to form an opening that produces the alveolar fricatives, voiceless [s] and voiced [z], as in sip and zip. The most usual [r] in British English is a fricative. The tip of the tongue is articulated against the back part of alveolar ridge and the vocal cords are made to vibrate. The sound is therefore described as a voiced post-alveolar fricative. Still farther back in the mouth, the front of the tongue can be raised towards the hard palate to form a narrow opening that produces the palatal fricatives, voiceless [ ʃ ] as in usher, sure and voiced [ʒ] as in azure and pleasure. The last member of the fricative group is [h]. This sound is produced when the mouth is held in a vowel-position and the air passes through the wide open glottis (opening between the vocal cords). It is known as a glottal fricative because friction is produced by the air passing through the glottis.
The description above can be summarized as follows:
Fricatives are produced when the air stream is not completely stopped but passes through with friction or a hissing sound.
--> Fricatives which are produced by the upper teeth (as the point of articulation) and the
lower lip which make the opening through which air passes with friction are called
labiodental fricatives. These sounds are [ f ] and [ v ]. [ v ] is voiced but [ f ] is
voiceless.
--> Fricatives which are produced by the tip of the tongue which shapes an opening with
the upper teeth are called dental fricatives. These sounds are [ θ ], and [ ð ]. [ ð ] is
voiced but [ θ ] is voiceless.
--> Fricatives which are produced when the tip of the tongue raised close to alveolar ridge
to form an opening that produces fricative sounds are called alveolar fricatives. These
sounds are [ s ] and [ z ] . [z ] is voiced but [ s ] is voiceless.
--> Fricative which is produced by the tip of the tongue which is articulated against the
back part of alveolar ridge and vocal cords are made to vibrate is called post alveolar
fricative. The voiced post alveolar fricative is [ r ].
--> Fricatives which are produced when the front of the tongue is raised towards the hard
palate to form a narrow opening that produces fricative sounds are called palatal
fricatives. These sounds are [ ʃ ] and [ʒ] . [ʒ] is voiced but [ ʃ ] is voiceless.
--> Fricative which is produced by the air passing through the glottis is called glottal
fricative. This sound is [ h ] which is voiceless.
Affricates. An affricate is produced when a stop combines with a fricative. There are only two affricates in English and they are formed with the tip of the tongue near the alveolar ridge. They are thus alveolar affricates, voiceless [ tʃ ] as in church and teacher, and voiced [ʤ] as in judge and badger.
Based on the description above, we can summarize as follows;
Affricates are produced when a stop continues with a fricative. These sounds are [ tʃ ] and [ʤ]. [ʤ] is voiced alveolar affricate but [ tʃ ] is voiceless alveolar affricate.
Nasals are produced with air stream passing through the nose. All nasal are voiced. The nasal sounds are:
[ m ] --> bilabial nasal -- when the mouth is closed by two lips and air issues through the nose.
[ n ] --> alveolar nasal -- when the air is stopped at the alveolar ridge.
[ ŋ ]--> velar nasal -- when the back of the tongue closes against the velum.
Lateral is produced when the air stream is stopped in the center by the tip of the tongue against the alveolar ridge, while the air passes along one or both sides of the tongue. This sound is [ l ] which is a voiced alveolar lateral.
Semi-vowels are the consonants which has the characteristics of vowels. These sounds are [ w ] and [ j ]. The English consonants can be summarized as follows.
Bilabial | Labio-dental | Dental | Alveolar | Post Alveolar | Palatal | Velar | Glottal | |
STOP | p, b | t, d | k, g | |||||
AFFRICATE | tʃ , ʤ | |||||||
NASAL | m | n | ŋ | |||||
LATERAL | l | |||||||
FRICATIVE | f, v | θ , ð | s, z | r | ʃ, ʒ | h | ||
SEMI-VOWEL | j |
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