There can be no doubt that we must have in our language the five vowels a, e, i, o, u, and only those, and that they must be pronounced with their continental values, which are found also in certain words in English, though English very often has shifted the values of the vowels. A thus must never be pronounced as in E tale, e never as in me, i never as in fine, o never as in do, u never as in but, etc. The proper sounds to be given to these signs are seen in the following examples:
a: E father, F la, part, D vater, fasse.
e: E yes, F père, été,
D sehn, denn.
i: E machine, in, F fille, ici, D
viel, in.
o: E so (cf. below), hot, F beau,
tôle, D so, von.
u: E rude, pull, F tout, jour, D du,
dumm.
A phonetician will easily see that the vowels given in these examples are not pronounced exactly alike, neither within the same language nor when we compare the three languages cited. But this is one of the beauties of an international language, that it needs only five vowels, and therefore can allow a certain amount of liberty in pronouncing these sounds without any misunderstanding arising, as is often the case in national languages when small differences are disregarded which are significant in the language itself but which cannot easily be kept apart by foreigners. It would be a serious mistake in an artificial language to distinguish an open and a close e (as in F chanté and chantais) or two a's (as in F patte and pâte). We must not give too strict rules for pronunciation, and the only thing on which we must insist is to make each vowel as clear as possible: a must neither be too near e nor too near o, etc. It is then for teachers to know and to tell their pupils where their particular language is apt to deviate from that clear and neutral pronunciation which will make it possible for their words to be understood by foreigners. Thus English people must be warned not to make vowels in unstressed syllables indistinct, as in banana, perceive, polite, suppose, and not to dipthongize long vowels, as in shade, home, so. Nor should they pronounce the short written o with too open a sound; especially in the mouth of many Americans not, stop sounds as containing a continental a rather than an o-sound.
The examples given contain long as well as short vowels: in an I.A.L. it would not do to have words solely distinguished by the length of the vowel, as is done so often in many languages, e.g. F maître, mettre, D biete, bitte. Such distinctions are unknown in some languages, and must be reckoned among those phonetic subtleties which would make an I.A.L. too difficult for practical use. We should therefore give no rule for the quantity of any vowel, but leave it to the convenience of each speaker separately, though it is inevitable that most nations would make, for instance, the o long in rose and short in poste. In this connexion we may also mention that it would be a fatal mistake to have double consonants in an I.A.L.: though some nations (e.g. Italians, Swedes, Finns) pronounce written double consonants so as to keep them easily distinct from single consonants, the same is not true of most other nations: neither E, D nor Dan pronounces t in bitter as a double (or long) consonant, and the spelling with two t's practically serves only to show the shortness of the preceding vowel. Therefore in Novial, as well as in Esp-Ido, we simplify the spelling in all words containing double letters in the national languages, from which the words are taken: pasa (E pass, F passer), efekte, komun (F commun, E common), etc. In this we follow the beautiful example of Spanish, which writes pasar, efecto, común, etc., and even extend it to cases in which Spanish makes a distinction in sound and spelling, as with ll and rr: bel S bello, F belle, koresponda, S corresponder, etc. We thus get rid of something which as a matter of fact presents very great difficulties to all spellers in English as well as in other languages.
The rounded front vowels found, e.g., in F pu, peu, peur, D über, höhe, Dan syn, sø, sön, are unknown in a great many important languages (E I S), and therefore inadmissible in a language that should be easy to many millions; the first of these vowels was what at first was meant by the letter y, which has now become [i] in many languages, and should therefore in the international language be spelt i as in I sistema, sintomo, sintesi (here sisteme, simptome, sintese); note also the spellings D Sc stil, I stilo, where E F have style, I S silvano = E sylvan, F sylvain.
Nasal vowels as in F an, vin, un, on cannot be tolerated in an I.A.L.
When two vowels occur side by side, each of them should be pronounced distinctly with its proper sound, thus eu in Europa, neutral with the sound of e in net + the sound of u in put or F fou, accordingly not like the D pronunciation of eu and of course not with the sounds of the same words in E. Here we have naturally a dipthong, and similarly in audi, boikota, etc. But whether the two vowels in naivi, arkaiki, kokaine, peisaje, fideikomise and other similar words are pronounced rapidly enough to form a dipthong or are kept apart, does not matter very much, so long as each of them is pronounced distinctly. The same is true of the combinations found in natione, filio, filia, sexual, vertuos, etc., which in rapid pronunciation tend towards a pronunciation with y and w respectively.