information:filtering, structural:reformatting, structural:scholar_edition
Null onset

Some languages forbid null onsets. In these languages, words beginning in a vowel, like the English word at, are impossible.

This is less strange than it may appear at first, as most such languages allow syllables to begin with a phonemic glottal stop (the sound in the middle of English uh-oh or, in some dialects, the double T in button, represented in the IPA as /ʔ/). In English, a word that begins with a vowel may be pronounced with an epenthetic glottal stop when following a pause, though the glottal stop may not be a phoneme in the language.

Few languages make a phonemic distinction between a word beginning with a vowel and a word beginning with a glottal stop followed by a vowel, since the distinction will generally only be audible following another word. However, Maltese and some Polynesian languages do make such a distinction, as in Hawaiian /ahi/ ('fire') and /ʔahi / ← /kahi/ ('tuna') and Maltese /∅/ ← Arabic /h/ and Maltese /k~ʔ/ ← Arabic /q/.

Ashkenazi and Sephardi Hebrew may commonly ignore א, ה and ע, and Arabic forbid empty onsets. The names Israel, Abel, Abraham, Omar, Abdullah, and Iraq appear not to have onsets in the first syllable, but in the original Hebrew and Arabic forms they actually begin with various consonants: the semivowel / j / in יִשְׂרָאֵל yisra'él, the glottal fricative in / h / הֶבֶל heḇel, the glottal stop / ʔ / in אַבְרָהָם 'aḇrāhām, or the pharyngeal fricative / ʕ / in عُمَر ʿumar, عَبْدُ ٱللّٰ ʿabdu llāh, and عِرَاق ʿirāq. Conversely, the Arrernte language of central Australia may prohibit onsets altogether; if so, all syllables have the underlying shape VC(C).

The difference between a syllable with a null onset and one beginning with a glottal stop is often purely a difference of phonological analysis, rather than the actual pronunciation of the syllable. In some cases, the pronunciation of a (putatively) vowel-initial word when following another word – particularly, whether or not a glottal stop is inserted – indicates whether the word should be considered to have a null onset. For example, many Romance languages such as Spanish never insert such a glottal stop, while English does so only some of the time, depending on factors such as conversation speed; in both cases, this suggests that the words in question are truly vowel-initial.

But there are exceptions here, too. For example, standard German (excluding many southern accents) and Arabic both require that a glottal stop be inserted between a word and a following, putatively vowel-initial word. Yet such words are perceived to begin with a vowel in German but a glottal stop in Arabic. The reason for this has to do with other properties of the two languages. For example, a glottal stop does not occur in other situations in German, e.g. before a consonant or at the end of word. On the other hand, in Arabic, not only does a glottal stop occur in such situations (e.g. Classical /saʔala/ "he asked", /raʔj/ "opinion", /dˤawʔ/ "light"), but it occurs in alternations that are clearly indicative of its phonemic status (cf. Classical /kaːtib/ "writer" vs. /mak tuːb/ "written", /ʔaːkil/ "eater" vs. /maʔkuːl/ "eaten"). In other words, while the glottal stop is predictable in German (inserted only if a stressed syllable would otherwise begin with a vowel), the same sound is a regular consonantal phoneme in Arabic. The status of this consonant in the respective writing systems corresponds to this difference: there is no reflex of the glottal stop in German orthography, but there is a letter in the Arabic alphabet (Hamza (ء)).

The writing system of a language may not correspond with the phonological analysis of the language in terms of its handling of (potentially) null onsets. For example, in some languages written in the Latin alphabet, an initial glottal stop is left unwritten (see the German example); on the other hand, some languages written using non-Latin alphabets such as abjads and abugidas have a special zero consonant to represent a null onset. As an example, in Hangul, the alphabet of the Korean language, a null onset is represented with ㅇ at the left or top section of a grapheme, as in 역 "station", pronounced yeok, where the diphthong yeo is the nucleus and k is the coda.