Speech sounds can be classified and described in articulatory, acoustic and auditory terms. On the basis of these terms the two broad categories in which the speech sounds in any language can be classified are vowels and consonants. Consonants are best described in articulatory terms because there is some type of closure or narrowing of the air passage to the extent that there is audible friction during the production of that sound. But in case of the production of vowels as there is no closure and no narrowing of the air passage to the extent that it may produce audible friction both articulatory and auditory terms are used to describe and classify them. In Phonetic terms vowels are speech sounds in the production of which there is no obstruction or closure and no narrowing of a degree that would cause audible friction in the pharynx and the mouth. Vowels are essentially a tone issuing from the glotis with the vocal chords vibrating. Classification and description of vowels becomes difficult due to the fact that the distinction of one vowel from another arises because of the modification in the shape and size of the resonating chambers, that is the pharyngeal cavity, nasal cavity and the mouth. Soft Palate, the lips and the tongue are responsible for this modification. Thus, just as any description of consonant sounds should reveal the position of vocal cords, place of articulation and manner of articulation, similarly any description of vowel sounds describe: 1. the position of the soft palate – raised (oral) or lowered (nasalized). 2. The shape of the lips –
i. Unrounded - spread, neutral, open
ii. Rounded – open and close
3. The shape of the tongue
i. which part of the tongue is raised – front, central and back. ii. How high is the part of the tongue is raised – close, half close, half open and open. The position of the soft palate is judged by auditory perception. The shape of the lips can be observed by the eye and...