Most European languages use some variation of the Latin alphabet. However, while most of them seem to broadly agree on what sounds most of the individual letters represent (with some minor differences, like whether or not /b d g/ are voiced, the exact phonetic value of /a/, etc.), some letters (including some digraphs) seem to have a lot of variance across languages. Some examples between English, German, Polish and (European) Spanish:
- ⟨j⟩ in Spanish represents /x/, which in German and Polish is written ⟨ch⟩ (also ⟨h⟩ in Polish); meanwhile, Polish and German ⟨j⟩ represents /j/, which is written ⟨y⟩ in English and Spanish; and English and Spanish ⟨ch⟩ represents /tʃ/, which is written ⟨tsch⟩ in German.
- Polish and German ⟨w⟩ represents /v/ like English ⟨v⟩, while English ⟨w⟩ represents /w/, written ⟨ł⟩ in Polish.
- ⟨x⟩ represents /ks/ in Polish, German and English (also /gz/ in English), but in Catalan it (mostly) represents /ʃ/ – which is written ⟨sh⟩ in English and ⟨sch⟩ in German.
- ⟨z⟩ represents /z/ in Polish and English, but /ts/ in German and /θ/ in Spanish; in English, /ts/ is written ⟨ts⟩ and /θ/ is ⟨th⟩, while in Polish, /ts/ is ⟨c⟩ (which in turn represents a mixture of /k/ and /s/ in English, /k/ and /θ/ in Spanish, and /k/ and /ts/ in German).
It has interested me for some years how many separate (single- and multi-language) groups there are of ways of pronouncing Latin letters (and whether that’s unique to Latin or is common also for, say, Cyrillic), but I can’t for the life of me even find the starting point to learn more.
So - what is the name of subdiscipline or theory that explores these differences in what pronunciations the letters of a single alphabet represent in different languages?
I don’t think the term I’m looking for is ‘orthographic depth’, since that concerns a single language in isolation, whereas I’m looking for commonalities and differences between several languages.