Iduna is an Austronesian language spoken on Goodenough Island of Milne Bay Province of Papua New Guinea.
The inventory of the Iduna language consists of 14 consonant phonemes.
Voiced plosives generally contrast with their unvoiced counterparts, except for the bilabial series, where varies freely between and . Moreover, the phoneme is commonly realized as , though for some speakers it may be pronounced as a voiced fricative without contrast. Finally, has also two allophonic realizations: occurs word-initially and word-medially before non-front vowels , or , whereas only appears before front vowels or . Other minor allophonic realizations may occur. Among these variations only the last one is reflected in the orthography.
There are five vowel phonemes in Iduna.
Vowels have allophones too. The major allophonic variations are described in the following table. These include the double realization of , which corresponds to when found in stressed syllables, while it approximates in unstressed environments, and the nasal allophonic variant of .
The language also has four monomoraic diphthongs: , , and . These are distinguished from vowel sequences, which instead are bimoraic, e.g. the word 'he scrapes it' contrasts with 'he unties it'.
In Iduna consonant clusters are forbidden; therefore, there are only open syllables of type V, CV and CVV. Also, the special kind of sequence CuV is generally interpreted as C÷V.
The Iduna alphabet is shown in the following table: