Igbo phonology

Igbo is a tonal language with two distinctive tones, high and low. In some cases a third, downstepped high tone is recognized. The language's tone system was given by John Goldsmith as an example of suprasegmental phenomena that go beyond the linear model of phonology laid out in The Sound Pattern of English. Igbo words may differ only in tone. An example is ákwá "cry", àkwà "bed", àkwá "egg", and ákwà "cloth". As tone is not normally written, these all appear as $⟨akwa⟩$ in print.

The language features vowel harmony with two sets of oral vowels distinguished by pharyngeal cavity size described in terms of retracted tongue root (RTR). These vowels also occupy different places in vowel space: (the last commonly transcribed, in keeping with neighboring languages). For simplicity, phonemic transcriptions typically choose only one of these parameters to be distinctive, either RTR as in the chart at right and Igbo orthography (that is, as ), or vowel space as in the alphabetic chart below (that is, as ). There are also nasal vowels.

Adjacent vowels usually undergo assimilation during speech. The sound of a preceding vowel, usually at the end of one word, merges in a rapid transition to the sound of the following vowel, particularly at the start of another word, giving the second vowel greater prominence in speech. Usually the first vowel (in the first word) is only slightly identifiable to listeners, usually undergoing centralisation. /Kà ó mésyá/, for example, becomes /kòó mésyá/ "goodbye". An exception to this assimilation may be with words ending in /a/ such as /nà/ in /nà àlà/, "on the ground", which could be completely assimilated leaving /n/ in rapid speech, as in "nàlà" or "n'àlà". In other dialects however, the instance of /a/ such as in "nà" in /ọ́ nà èrí ńrí/, "he/she/it is eating", results in a long vowel, /ọ́ nèèrí ńrí/.

Igbo does not have a contrast among voiced occlusives (between voiced stops and nasals): the one precedes oral vowels, and the other nasal vowels. Only a limited number of consonants occur before nasal vowels, including.

In some dialects, such as Enu-Onitsha Igbo, the doubly articulated and  are realized as a voiced/devoiced bilabial implosive. The approximant is realized as an alveolar tap  between vowels as in árá. The Enu-Onitsha Igbo dialect is very much similar to Enuani spoken among the Igbo-Anioma people in Delta State.

To illustrate the effect of phonological analysis, the following inventory of a typical Central dialect is taken from Clark (1990). Nasality has been analyzed as a feature of consonants, rather than vowels, avoiding the problem of why so few consonants occur before nasal vowels; has also been analyzed as.

Syllables are of the form (C)V (optional consonant, vowel) or N (a syllabic nasal). CV is the most common syllable type. Every syllable bears a tone. Consonant clusters do not occur. The semivowels and  can occur between consonant and vowel in some syllables. The semi-vowel in is analyzed as an underlying vowel "ị", so that -bịa is the phonemic form of bjá 'come'. On the other hand, "w" in is analyzed as an instance of labialization; so the phonemic form of the verb -gwá "tell" is.