WHY DO SOME GLOSA WORDS HAVE MOBILE CONSONANTS?
Short answer: Professor Lacelot Hogben wanted Glosa to be a spoken language.
Some Glosa words add a consonant before the vowels (A, E, I, O, U) and H. The words are U(N), A(D), and NO(N). (E(X) has been dropped from the original Interglossa language.)
Hogben knew how useful these are in natural languages. In many languages, people tend to blend vowels together. Inserting the mobile (meaning "sometimes") consonant keeps speakers from slopping the vowels together, so the listener hears two distinct syllables instead of one. Although the speaker of Glosa may find this troublesome, it is designed to make it easier for the LISTENER.