Benjamin Franklin's phonetic alphabet as follows: Franklin's proposed alphabet included seven letters to represent vowels. This set consisted of two new letters, in addition to five letters from the existing English alphabet: a, e, i, o, u. The first new letter was a formed as a ligature of the letters o and a, and used to represent the sound (as written in IPA). The second, ɥ, was used for . Franklin proposed the use of doubled letters to represent what he called long vowels, represented by modern phonemes thus: as the long-vowel variant for (or, in his notation, "cɩcɩ" versus "cɩ"), for ("ee" versus
Cardinal vowels the opposite side of the front-back dimension, so that e.g. Cardinal 1 can be produced with rounding somewhat similar to that of Cardinal 8 (though normally compressed rather than protruded); these are known as 'secondary cardinal vowels'. Sounds such as these are claimed to be less common in the world's languages. Other vowel sounds are also recognised on the vowel chart of the International Phonetic Alphabet. In the , the cardinal vowels have the same numbers used above, but added to 300. The usual explanation of the cardinal vowel system implies that the competent user can reliably distinguish between sixteen