A phonemic orthography is an orthography in which the graphemes correspond consistently to the language's phonemes, or more generally to the language's diaphonemes. [1] Phonemic orthographies have the highest possible level of orthographic depth, as they have exact letter to phoneme correspondence.
For a systemic analysis of the phoneme/grapheme correspondence, Petr Sgall distinguishes two conditions, both of which are to be satisfied for a phonemic orthography: [2]
Under these conditions, even orthographies with exceptionally high orthographic depth, such as Italian and Welsh, are excluded due to their use of digraphs, which change the pronunciation of some grapheme based on surrounding graphemes. For example, the grapheme ⟨ n ⟩ is usually pronounced as /n/ in Welsh, but the digraph ⟨nh⟩ is pronounced as /n̥/; [3] [4] therefore, ⟨n⟩ does not always represent the same phoneme, and thus the orthography is not fully phonemic.
In the past, the term phonetic orthography was used to refer to various proposals of phonetic English-language spelling reforms, [5] e.g., by J.I.D. Hinds [6] [7] or Tobias Witmer. [8]
On the other hand, Morris Swadesh defined "phonetic orthography" or "phonetic alphabet" as a writing system to make a phonetic record using symbols for "selected characteristic points in the total range of possible speech sounds", [1] : 365 this is more commonly referred to as "phonetic transcription".