Coptic sounds

Coptic provides the clearest indication of Later Egyptian phonology, thanks to its writing system, which fully indicates vowel sounds and occasionally stress pattern. The phonological system of Later Egyptian is also better known than that of the Classical phase of the language due to a greater number of sources indicating Egyptian sounds, including cuneiform letters containing transcriptions of Egyptian words and phrases, and Egyptian renderings of Northwest Semitic names. Coptic sounds, in addition, are known from a variety of Coptic-Arabic papyri in which Arabic letters were used to transcribe Coptic and vice versa. They date to the medieval Islamic period, when Coptic was still spoken.

Vowels
There are some differences of opinion among Coptic language scholars on the correct phonetic interpretation of the writing system of Coptic. Differences center on how to interpret the pairs of letters ε/η and ο/ω. In Greek spelling, the first member of each pair is a short closed vowel and the second member is a long open vowel. In some interpretations of Coptic phonology (Plumley 1948), it is assumed that the length difference is primary. Thus ε/η is and ο/ω is. Other scholars (Greenberg 1962/1990, Lambdin 1983:xii-ix) argue for a different analysis in which ε/η and ο/ω are interpreted as and.

The following two charts show the two theories of Coptic vowel phonology.

In the Upper Egyptian dialects, a superlinear stroke is placed over sonorants to mark a reduced. This vowel does not undergo reduction in northern dialects, where it is indicated by in Bohairic and  or  in Fayyumic. For example, 'to worship' is SahLyc, Bohairic  and Fayyumic. The vowel quality of can vary: either  or  depending on the dialect. In Sahidic and other Upper Egyptian dialects, word-final corresponds to word-final  in the northern dialects.

The vowel is typically represented by —its presence may be an indicator of emphasis spread in the same syllable. For example, (used in the construction 'man of [trade]') is transcribed $\langle\rangle$ in medieval Coptic-Arabic papyri. In some phonetic environments, is a more open, and  is a more forward. The vowel is always unstressed and can be reduced to zero as in earlier Egyptian scripts, which did not indicate unstressed and most stressed vowels.

Coptic also has three to four diphthongs – mainly, and  – although these may be interpreted as series of vowels and glides. In some dialects, they are monophthongized.

Consonants
As with the vowels, there are differences of opinion over the correct interpretation of the Coptic consonant letters, particular the letters ϫ and Ϭ. The letter ϫ is transcribed as $\langlej\rangle$ in many older Coptic sources and Ϭ as (Plumley 1947) or. Lambdin (1983) notes that the current conventional pronunciations are different from the probable ancient pronunciations: ϫ was probably pronounced and Ϭ was probably pronounced. Reintges (2004:22) suggests that ϫ was pronounced.

The following chart shows the consonants that are represented in Sahidic Coptic orthography. Consonants that are rare, or found primarily in Greek loanwords are shown in parentheses:

Bohairic Coptic has an additional consonant,, spelled Ϧ. It is possible that in the ancient pronunciation of Coptic that there were additional consonants which were not spelled in the writing system, such as.

Earlier phases of Egyptian may have contrasted voiceless and voiced bilabial plosives, but the distinction seems to have been lost. Late Egyptian, Demotic and Coptic all interchangeably use their respective graphemes to indicate either sound – for example, Coptic for 'iron' appears alternately as, and. This probably reflects dialect variation. Both letters were interchanged with and  to indicate, and  was also used in many texts to indicate the bilabial approximant. Coptologists believe that Coptic was articulated as a voiced bilabial fricative. In the present-day Coptic Church services, this letter is realized as, though this is almost certainly a result of the pronunciation reforms instituted in the 19th century.

Whereas Old Egyptian contrasts and, the two sounds appear to be in free variation in Coptic, as they were since the Middle Egyptian period. However, they are contrasted only in Greek loans; for example, native Coptic (') and  (') 'school' are homophonous. Other consonants that sometimes appear to be either in free variation or to have different distributions across dialects are and,  and  (especially in the Fayyumic dialect – a feature of earlier Egyptian) and  and , with the voiceless plosives being more common in Coptic words and the voiced ones in Greek borrowings. Apart from the liquid consonants, this pattern may indicate a phonological change in Later Egyptian leading to a neutralization of voiced alveolar and velar plosives. When the voiced plosives are realized, it is usually the result of sonorization in proximity to.

Old Coptic texts graphically express the Egyptian pharyngeals in a variety of ways. For example, the Old Coptic grapheme was occasionally used to convey a voiceless pharyngeal fricative. In literary Coptic, the two sounds are not indicated by separate letters, suggesting loss of phonemic status. Instead, the adapted demotic grapheme, which normally stands for , is used to express either sound. In unstressed initial syllables and stressed final syllables, the voiced pharyngeal fricative is sometimes conveyed by as in  () 'to multiply'. Similarly, different methods are employed to graphically express the glottal stop: with word-initially, with  word-finally in monosyllabic words in northern dialects and  in monosyllabic words in Akhmimic and Assiutic, by reduplication of a vowel's grapheme, but mostly as.