cardinal vowel no. I has the symbol [i], and is defined as the vowel which is as close and as front as is possible to make a vowel without obstructing the flow of air enough to produce friction noise; friction noise is the sort of hissing sound that one hears in consonants like s or f. Cardinal vowel no.5 has the symbol [ ] and is defined as the most open and back vowel that it is possible to make. Cardinal vowel no.8 [u], is fully close and back and no.4 [a], is fully open and front. After establishing these extreme points, it is possible to put in intermediate points. Many students when they hear these vowels find that they sound strange and exaggerated; you must remember that they are extremes of vowel quality.