In linguistics, an alphaphonetic pronunciation is the pronunciation of an alphabetical glyph ("letter") with the canonical pronunciation employed in learning the alphabet, rather than in accord with other morphological variants. It is a concept within phonemic orthography, particularly with the pronunciation of vowels, in which the alphabetic pronunciation of a letter name is taken as a default and employed in the pronunciation of particular words spelled with that letter. Phonological change may be constrained by the influence of canonical alphabet pronunciation.
In languages such as English in which many words have several morphophonemic variants, the pronunciation of the letters of the alphabet influences an invariant "alphaphonemic pronunciation" of words. The concept is less relevant to languages like Spanish in which the phonemic orthographies are always alphaphonemic, and thus no distinctions are relevant. The latter type of languages may be said to have "good" or "1:1" grapheme-to-phoneme correspondence.
For example, the letter "a," in English alphaphonemic pronunciation, is pronounced /eɪ/ and not /ɑː/ as in Latin-based languages. Hence a word like "amen," which in its original Latin alphaphonemic pronunciation is pronounced /ˌɑːˈmɛn/ ("ah-men"), in English it is often pronounced /ˌeɪˈmɛn/ ("A-men"). In both American and British English, the English alphaphonemic pronunciation /ˌeɪˈmɛn/ is colloquially (if not formally) dominant, while the /ˌɑːˈmɛn/ pronunciation is typically regarded as "Latin" or "Latinized" (which, in context of Protestantism, may carry a certain negative connotation of Roman Catholic culture and influence).
The English alphaphonemic pronunciation of many words can be confusing to non-English speakers. The letter "i" in English words like "light" /ˈlaɪt/, "bicycle" /ˈbaɪsɨkəl/, "triad" /ˈtraɪ.æd/, "final" /ˈfaɪnəl/, and "spike" /ˈspaɪk/ are all pronounced alphaphonemically, and thus differ particularly from other orthographies. (The historic basis for this is in the Great Vowel Shift.) For example with Latin-based language speakers, a Latin-based pronunciation of "i" is constant, and considers "i" to always indicate /i/ or /iː/. In Latin orthography, the English alphaphonemic "I" /aɪ/ is spelled "ai," not "i," thus the Latin orthographic transcription of English pronunciations would be close the IPA examples above, while their native pronunciations of these English words would unintelligible (variations from English digraphs, etc. isolated in [brackets],): "light" /ˈliː[x]t/, "bicycle" /ˈbiːsikl[ɛ]/, "triad" /ˈtriː[aː]d/, "final" /ˈfiːn[aː]l/, and "spike" /ˈspiːk[ɛ]/.
As these examples show, because English alphaphonemics deviate significantly from Latinate pronunciations, the correspondence of English word spellings with their correct English pronunciations are not intuitively obvious to a learner.