77. It will be seen that in front vowels the “front” of the tongue is raised in the direction of the hard palate, while in back vowels the “back” of the tongue is raised in the direction of the soft palate.
78. Vowels in which the highest point of the tongue is well within the triangle, and intermediate in position between back and front, are called mixed vowels. An example of a mixed vowel is the vowel in bird. (It is not necessary to distinguish more than this one intermediate degree between back vowels and front vowels.)
79. In the above system of classification into the three divisions front, mixed and back, the vowels are classed according to the part of the tongue which is most raised. Vowels may also be classed according to the height to which the tongue is raised.
80. When we classify vowels according to the height to which the tongue is raised, we distinguish the following classes.
(i) Close vowels, viz. those in which the tongue is as high as possible consistently with not producing audible friction: example the English iː (the vowel in see).
(ii) Open vowels, viz. those in which the tongue is as low as possible: example the English ɔ (the vowel in not).
81. We distinguish further two intermediate positions, which we call (iii) Half-close and (iv) Half-open vowels, in which the tongue is lowered from the close position to about one-third, and two-thirds of the total distance from the close position to the open position; an example of a half-close vowel is the English e (the first element of the diphthong in day); an example a half-open vowel is ɛ (the first element of the diphthong in fair).
Fig. 11. The Classification of Vowels.
82. Fig. 11, which is a elaboration of the vowel triangle (fig. 9), will help to make clear the basis of the classification of vowels.
83. The positions of the tongue in the formation of the different vowel sounds may, to a large extent, be felt, and in many cases they may be seen by means of a looking-glass. They may also be determined experimentally in various ways.
*84. Atkinson’s Mouth Measurer[1], fig. 12, is a convenient instrument for this purpose. AB is a narrow metal tube 16 cm. long, of the shape shown in fig. 12, furnished with a slot 4.5 cm. long extending from A to C. Within the tube is a wire having at the lower end a handle D which projects through the slot and enables the observer
- ↑ Obtainable from H.W. Atkinson Esq., West View, Eastbury Avenue, Northwood, Middlesex, England. The price of the set of two instruments with necessary fittings is 5s. 6d. post free.
