| Old Irish had distinctive vowel length in both monophthongs and diphthongs. |
| In some languages, due to monophthongization, graphemes that originally represented diphthongs now represent monophthongs. |
| Younger women use the monophthongs characteristic of male speech. |
| The language has both monophthongs and diphthongs, and consonants can be voiced or unvoiced. |
| Diphthongs contrast with monophthongs, where the tongue or other speech organs do not move and the syllable contains only a single vowel sound. |
| The monophthongs and diphthongs total 14 vowel sounds, perhaps the smallest vowel system of any long-established variety of English. |
