IPA Cardinal Vowels are a series of eight basic vowels of known formation and acoustic qualities,which serve as a standard of measurement,and by reference to which other vowels can be described.They are of great importance to Chinese learners of English as second language learning. Once students are familiar with the position and mouth of those vowels,they can easily avoid mispronouncing them in a Chinese way. IPA Cardinal Vowels are a series of eight basic vowels of known formation and acoustic qualities, which serve as a standard of measurement, and by reference to which other vowels can be described.They are of great importance to Chinese learners of English as second language learning Once students are familiar with the position and mouth of those vowels, they can easily avoid mispronouncing them in a Chinese way.