Acehnese, the language spoken by the Acehnese people of Aceh, Indonesia, has a large vowel inventory compared to Indonesian, with ten oral monophthong vowels,^[1] twelve oral diphthongs,^[2] seven nasal monophthong vowels,^[3] and five nasal diphthongs.^[4]

Native-speaking linguists divide vowels in Acehnese into several categories: oral monophthongs, oral diphthongs (which are further divided into the ones ending with /ə/ and with /i/), nasal monophthongs, and nasal diphthongs.^[5]

The table below shows the Acehnese consonant phonemes and the range of their realizations.^[10]

Notes:

• Syllable-final k always represents /ʔ/ save in certain recent loans
• /f/, /z/, and /ʃ/ are borrowed sounds, and are often replaced by /ph/, /d/, and /ch/ respectively
• The nasals /m/, /n/, /ɲ/, /ŋ/ are realized as post-stopped nasals (also called "funny nasals") before oral vowels and consonants.^[11][12] They are distinct from the nasal-stop sequences /mb/, /nd/, /ɲɟ/, /ŋɡ/, e.g. in /banᵈa/ 'port' vs /mandum/ 'all'.^[13] The orthography does not distinguish these sounds.

The orthography of Achenese features 31 letters: the 26 letters of the basic Latin alphabet, è, é, ë, ô, and ö.