|Native to||Papua New Guinea|
|Region||Milne Bay Province (Goodenough Island)|
|(6,000 cited 1984)|
Voiced plosives generally contrast with their unvoiced counterparts, except for the bilabial series, where /b/ varies freely between [b] and [p]. Moreover, the phoneme /g/ is commonly realized as [g], though for some speakers it may be pronounced as a voiced fricative [ɣ] without contrast. Finally, /t/ has also two allophonic realizations: [t] occurs word initially and word medially before non-front vowels /a/, /o/ or /u/, whereas [s] only appears before front vowels /i/ or /e/. Other minor allophonic realizations may occur. Among these variations only the last one is reflected in the orthography.
|/b/||[b ~ p], [bʷ]||free variant; [bʷ] before non-syllabic /u/|
|/f/||[f], [fʷ]||Normally [f]; [fʷ] before non-syllabic /u/|
|/k/||[k], [kʷ]||Normally [k]; [kʷ] before non-syllabic /u/|
|/g/||[g ~ ɣ], [gʷ]||free variant; [gʷ] before non-syllabic /u/|
|/t/||[t], [s]||[s] before /i/ and /e/; [t] elsewhere|
|/d/||[d], [tʰ]||[tʰ] before /i/ in final syllable position only; [d] elsewhere|
|/m/||[m], [mʷ]||Normally [m]; [mʷ] before non-syllabic /u/|
Vowels have allophones too. The major allophonic variations are described in the following table. These include the double realization of /a/, which corresponds to [a] when found in stressed syllables, while it approximates [ʌ] in unstressed environments, and the nasal allophonic variant of /u/.
|/a/||[a], [ʌ]||[a] in stressed syllable; [ʌ] elsewhere|
|/u/||[u], [ũ]||[ũ] following /m/; [u] elsewhere|
The language also has 4 monomoraic diphthongs: /ai/, /au/, /ao/ and /oi/. These are distinguished from vowel sequences, which instead are bimoraic, e.g. the word giyauna [gi.jau.nʌ] "he scrapes it" contrasts with giyauna [gi.ja.u.nʌ] "he unties it".
The Iduna alphabet is shown in the following table:
|A a||B b||D d||E e||F f||G g||H h||I i||L l|
|M m||O o||S s||T t||U u||V v||W w||Y y||ʼ|
- Sampson, Nancy; Huckett, Joyce (1965). Vivigani Phonemes (PDF) (draft). Ukarumpa: Summer Institute of Linguistics (SIL). Retrieved February 21, 2019.
- Huckett, Joyce (1974). "Notes on Iduna Grammar" (PDF). In Healey, Alan (ed.). Three studies in languages of eastern Papua. Workpapers in Papua New Guinea Languages 3. Ukarumpa: Summer Institute of Linguistics (SIL). pp. 63–133. Retrieved February 21, 2019.
- Huckett, Joyce (1976). "Iduna Sentence Structure" (PDF). In Loving, Richard (ed.). Grammatical studies in Suena and Iduna. Workpapers in Papua New Guinea Languages 15. Ukarumpa: Summer Institute of Linguistics (SIL). pp. 127–262. Retrieved February 21, 2019.
- Huckett, Joyce (n.d.). Vivigani language lessons (PDF) (draft). Papua New Guinea: Summer Institute of Linguistics (SIL). Retrieved February 21, 2019.