Jespersen is well-known as a phonetician. In his Novial he has applied phonetic spelling with the known Latin alphabet. He discarded the double pronunciation of t (t in `tea', t in `-tion']. T in Novial is always pronounced as in `tea'. He retained the letter x as a convenient and internationally known symbol for the sounds `ks' and `gz'; q was retained in combination with u; y was discarded as a vowel and used as in English [`yes']; g was assigned the hard pronunciation as in `garden,' never as in `general.' His principle was `One symbol, one function.' These rules are identical with those of Ido. The letter c was treated by him in a novel way: k is used where the `k'-sound is required [kultur `culture'] and s where the `s'-sound is needed [sirkle `circle']. C disappears completely from the vocabulary of phonetic Novial. He quotes a few English examples in which s is used as well as c [licence, license; practice, practise; prophecy, prophesy]. The digraph ch is retained to spell many words which are needed in Novial.
Jespersen treats the letter z in the same way as c, he abolishes it and substitutes s, for he sees no other way out of the difficulty. He argues that the two sounds are not two phonemes, i.e., they do not serve to distinguish words in Novial. In Novial the two sounds may be used indiscriminately. Proper names, however, retain their original spelling [Cincinnati, Ibañez, Szczebrzeszyn, Poincaré].