What are cardinal vowels in relation to English vowels?
Cardinal vowels are a linguistic construction devised by Daniel Jones to organize a consistent vowel sound classification. The classification of vowel sounds in the cardinal organization is based on two possible tongue positions. These are the front-to-back and high-to-low positions. Front-to-back signifies the positions of the tongue that range from farthest forward at the teeth to farthest backward at the throat in vowel formations. High-to-low signifies the positions of the tongue that range from closest to the palette of the mouth to the furthest from the palette in vowel formations.
These two possible positions, front-to-back and high-to-low, always actualize in pairs on any vowel. So the cardinal vowels are recorded on the cardinal quadrilateral chart (the quadrilateral is a visualization of the perceived increasing size and shape of the mouth while pronouncing vowel sounds) between the two extreme sounds represented by the pairs high front and low back (highest and forward most tongue position to lowest and furthest back tongue position).
The vowels of all languages can be located within the variations of this cardinal quadrilateral for purposes of language transcription. Since the cardinal system is imperfect and rigid, very narrow, precise transcriptions are needed to record the deviations from the Primary and Secondary cardinal vowels in various languages.
In English, the cardinal vowels are linked to lexical sets to standardize the perceptions of vowel location along the high front to low back position pairs. All English varieties employ the same phonemes, but not all varieties employ the phonemes in the same words. For example, in British English (BE), Received Pronunciation, the word happy has an /i/ phoneme pronounced at the orthographic /y/, whereas American English (AE), General American, has an /I/ phoneme pronounced at the orthographic /y/. Another example, one using a consonant diphthong, is that in Indian English, the BE fricative /th/ phoneme is realized as a dental plosive.
Since all English varieties use the same phonemes, each Primary and Secondary vowel is assigned a lexical key word to standardized its position on the high front to low back quadrilateral chart. Of the eight Primary cardinal vowels, the high front vowel is /i/ as in BE pronunciation of the lexical pair word Happy. It is front high tense. The next is /e/ as in the diphthong in Face. It is front mid tense. Then comes the front mid lax sound as in the /e/ in Letter. The last of the four high front vowel classifications is the front low vowel as in the AE pronunciation of Palm.
Switching to the four low back classifications, the lowest one, the low back vowel, sounds like the AE pronunciation of Lot. The next highest position is back low open-o as in the AE pronunciation of the lexical pair word Cloth. It is back mid lax. Next is the low back /o/ sound in AE Goat. It is back mid tense. The highest of the low back pairs is /u/ as in the AE lexical pair word Goose. It is back high tense.