Every language possesses vowel sounds that play an inevitable role in producing speech. Vowel is one of the two general categories used for the classification of speech sounds, and this type of sound is articulated with the air from the lungs passing through the vibrating glottis and the vocal tract without any interruption.
That is, the speech sounds that are produced without any obstacles in the vocal tract are called vowels. However, vowels can be defined in terms of both phonetics and phonology.
Phonetically, they are sounds articulated without a complete
closure in the mouth or a degree of narrowing which would produce audible
friction; the air escaped evenly over the center of the tongue. If lung air
escapes solely through the mouth, the vowels are said to be oral; if some air
is simultaneously released through the nose, the vowels are nasal. On the other
hand, from a phonological point of view, vowels are those units that function
at the center of syllables. In other words, to form a syllable, at least one
vowel is indispensable. In establishing the vowel system of a language, several
dimensions of classification are used:
a. Duration of the vowel - whether long or short.
b. During an articulation, there is any detectable change in
quality - where vowels are classified under the headings - monophthong,
diphthong, and triphthong.
To conclude, these sounds can be long or short, rounded or unrounded,
front or back, close or open, central or centralized, simple or compound and so
on. However, English vowels are basically divided into two types - monophthong
and diphthong. And a third type - triphthong - can also be considered.
Monophthongs
'Monophthong' is a term used in phonetic classification of
vowel sounds on the basis of their manner of articulation. That is, a monophthong
is a simple or pure vowel articulated without any obstacles in the vocal tract.
The English language has twelve monophthongs as listed below:
1./i: /as in the words bean, leap, sheep, eat, seen, beat,
heat, read, deed, seed, meet, feed, deep, cheap, meal, heal, etc.
2. / I / as in the words bin, fin, din, dip, kid, mid, lip, ship, it, sin, bit, hit,
chip, mill,
Hill, kill, etc.
3. /e/ as in the words men, pen, ten, den, hen, tend, etc.
4./æ/as in the words man, pan, tan, fan, rank, pant, sand,
prank etc.
5./Λ /as in the words cut, nut, shut, mud, but, hut, etc.
6. /a:/as in the words bard, card, farm, hard, father
7. / a/ as in the words dog, pot, fog, etc
8. /ɔ:/as in the words lord, cord, short, etc.
9. / ǝ/as in the words ago,
today, perhaps, etc.
10. /3:/as in the words bird, girl, shirt, etc.
11. / ʋ /as in the words book, look, cook, etc.
12. /u:/as in the words fool, cool, tool, etc.
The first monophthong /I: / as in the words bean, leap,
sheep. etc. is pronounced in the front part of the vocal tract with the lips in
a relatively close and spread position. This is a long vowel.
The second monophthong / I /as in the words bin, lip, ship,
it, etc., is produced in the front-centralized part of the vocal tract with the
lips in a half-close and spread position. This is a short vowel.
The third monophthong / e /as in the words men, pen, ten, etc., is articulated in the front part of the vocal tract with the lips in their mid
and spread position. This is a short vowel.
The fourth monophthong / æ /as in the words man, pan, tan, etc., is pronounced in the front part of the vocal tract with the lips in a half open
and spread position. This is also a short vowel.
The fifth monophthong / Λ / as in the words cut, nut, shut, etc., is articulated in the central part of the vocal tract with the lips in a half-open position. It is a short vowel.
The sixth monophthong / a: /as in the words bard, card,
farm, etc., is produced in the back part of the vocal tract with the lips with
their completely open and spread position. It is a long vowel.
The seventh monophthong / a/as in the words dog, pot, fog, etc., is articulated in the back part of the vocal tract with the lips in a half open
and rounded position. It is a short vowel.
The eighth monophthong / ɔ:/as in the words lord, cord, short, etc., is produced in the back part of the vocal tract with the lips in their mid and rounded position. It is a long vowel.
The ninth monophthong / ǝ /as in the words ago, today ,perhaps, etc. is pronounced in the central part of the vocal tract with the lips in their mid position. It is the shortest vowel in the English language.
The tenth monophthong / 3: /as in the words bird, girl,
shirt, etc. is produced in the central part of the vocal tract with the lips in
their mid position. It is a long vowel.
The eleventh monophthong / u /as in the words book, look, cook,
etc. is articulated in the back-centralized part of the vocal tract with the
lips in their half-close and rounded position. It is a short vowel.
The twelfth monophthong / u: /as in the words fool, cool,
tool, etc. is pronounced in the back part of the vocal tract with the lips in
their close and rounded position. It is a long vowel.
Diphthongs
A diphthong is a speech sound that is usually considered as
one distinctive vowel of a particular language. But, in fact, it involves two
pure vowels or monophthongs, with one vowel gliding into the other.
For example, the diphthong / ai / in the English word 'my' /maI
/consists of the vowel /a:/ gliding into the vowel / I /. The English language
has eight diphthongal phonemes:
1. / eI/ as in the words may, tray, lay, etc.
2. / aI / as in the words hi, tie, cry, etc.
3. /ɔI/ as in the words boy, toy, joy, etc.
4. / Iǝ / as in the words deer, ear, tears, etc.
5. / eǝ / as in the
words care, air, tear, etc.
6. / ʋǝ / as in the
words poor, tour, sure, etc.
7. /eʋ / as in the
words so, no, go, etc.
8. / aʋ / as in the
words how, cow, now, etc.
The centering diphthongs glide towards / ǝ /:
(i) / Iǝ/: (e.g. beard, near, etc.): The glide of RP / Iǝ/ begins with a tongue position approximately as that used for /ı/, i.e. centralized, front, half-close, and moves in the direction of the more open variety of /ǝ / when /ǝ/ is final in the word, e.g. in 'near'; in non-final positions, e.g. in 'beard' the glide may not be so extensive, the quality of the /ǝ/ element being of a mid type. The lips are neutral throughout, with a slight movement from spread to open.
(ii) /eǝ /: (e.g. air, share, etc): The glide of / eǝ
/begins in the /e/position, and moves in the direction of the more open variety
of /ǝ /, especially when the diphthong is final; where / eǝ/ occurs in a syllable closed by a consonant,
the [e] element tends to be of a mid [ǝ] type. The lips are neutrally open
throughout.
(iii) / ʋǝ/: (e.g. poor, pure, etc): RP / ve / glides from a
tongue position similar to that used for / u /towards the more open type of / ǝ
/, and a somewhat closer variety of / ǝ/when the diphthong occurs in a closed
syllable.
Three closing diphthongs glide towards / I /and the
remaining two towards / ʋ/:
(ii) /aı /: (e. g. time, die, by, etc.): The RP glide begins at a point slightly behind the front open position, and moves towards the position associated with RP / I /. The lips change from a neutral to a loosely spread position.
(lii) /ɔI/: (e. g. boy, toy, joy, etc.): For RP /51/, the
tongue glide begins at a point associated with /ɔ: /, and moves towards the
position of / I /; the lips opening rounded for the first element changing to
neutral for the second.
The closing
diphthongs glide towards / ʋ/
(i) / ǝʋ /: (e. g. so, no, go, etc.): The glide of RP / ǝʋ /
begins at a mid-central position, and moves in the direction of RP / ʋ/, there
being a slight closing movement of the lower jaw. The lips are neutral for the
first element, but have a tendency to round on the second element.
(ii) / aʋ /: (e. g. how, town, house, etc.): The glide of RP
/ aʋ/ begins at a point between the back and front open positions, and moves
towards the position for RP / U /. The lips change from a neutrally open to a
weakly rounded position.
Each of some complex vowels is found to be made up of three monophthongs.
The English language has such vowels that are very difficult to recognize and
pronounce. However, a triphthong can be defined as a combination of three pure
vowels or monophthongs, in which the first one glides into the second one, and
then the second one, preceded by the first one, glides into the third one.
For example, / a: / glides into / ʋ/, and then / ʋ/ preceded by / a: / glides into /ǝ /, and thus the triphthong / aʋǝ / is constituted, as in the word 'hour'. The English language possesses five triphthongs:
2. / aIǝ/ as in the words liar, fire, tyre, etc.
3. / ɔIǝ/ as in the words loyal, royal, etc.
4./ǝʋǝ/ as in the words lower, mower, slower, etc.
5. / aʋǝ / as in the
words tower, power, hour, etc.
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