Consonants

Nauruan has 16–17 consonant phonemes. Nauruan makes phonemic contrasts between velarized and palatalized labial consonants. Velarization is not apparent before long back vowels and palatalization is not apparent before non-low front vowels.^[6]

Voiceless stops are geminated and nasals also contrast in length.^[9] Dental stops /t/ and /d/ become [tʃ] and [dʒ] respectively before high front vowels.^[10]

The approximants become fricatives in "emphatic pronunciation." Nathan (1974) transcribes them as ⟨j⟩ and ⟨w⟩ but also remarks that they contrast with the non-syllabic allophones of the high vowels. /w/ can also be heard as a fricative [ɣʷ].

Depending on stress, /r/ may be a flap or a trill. The precise phonetic nature of /rʲ/ is unknown. Nathan (1974) transcribes it as ⟨r̵⟩ and speculates that it may pattern like palatalized consonants and be partially devoiced.

Between a vowel and word-final /mˠ/, an epenthetic [b] appears.^[6]

Vowels

There are 12 phonemic vowels (six long, six short). In addition to the allophony in the following table from Nathan (1974), a number of vowels reduce to [ə]:^[7]

Non-open vowels (that is, all but /aa/, /a/, /ɑɑ/ /ɑ/) become non-syllabic when preceding another vowel, as in /e-oeeoun/ → [ɛ̃õ̯ɛ̃õ̯ʊn] ('hide').^[11]

Stress

Stress is on the penultimate syllable when the final syllable ends in a vowel, on the last syllable when it ends in a consonant, and initial with reduplications.^[7]

Attempt at language reform of 1938

In 1938, there was an attempt by the Nauruan language committee and Timothy Detudamo to make the language easier to read for Europeans and Americans. It was intended to introduce as many diacritical symbols as possible for the different vowel sounds to state the variety of the Nauruan language^{[clarification needed]} in writing. It was decided to introduce only a circumflex accent in the place of the former tilde, so that the characters "õ" and "ũ" were replaced by "ô" and "û". The "ã" was replaced with "e".

Also, "y" was introduced in order to differentiate words with the English "j" (puji). Thus, words like ijeiji were changed to iyeyi. In addition, "ñ" (which represented the velar nasal) was replaced with "ng", to avoid confusion with the Spanish Ñ. "bu" and "qu" were replaced with "bw" and "kw", respectively. "ts" was replaced with "j" (since it represented a sound similar to the English "j"); and the "w" written at the end of words was dropped.

These reforms were only partly carried out: the symbols "õ" and "ũ" are still written as such, with tildes. However, the letters "ã" and "ñ" are now only seldom used, being replaced with "e" and "ng", as prescribed by the reform. Likewise, use of the digraphs "bw" and "kw" has been implemented. Although "j" took the place of "ts", certain spellings still use "ts": e.g., the districts Baiti and Ijuw (according to the reform Beiji and Iyu) are still written with the old writing conventions. The "y" has become generally accepted.

Today the following 30 Latin letters are used.

• Vowels: a, ã, e, i, o, õ, u, ũ
• Consonants: b, c, d, f, g, h, j, k, l, m, n, ñ, p, q, r, s, t, v, w, x, y, z

The relationship of the above letters and phonemes is:^{[12][better source needed]} a [ɑ/a], ã [ɛ], e [e/e̞/ɛ], i [i/ɪ/ɨ], o [o/ɔ], õ [ø], u [ʊ/ʉ], ũ [y], b [b], bw [b͡w], c [k/s], d [d], di [ʤi], f [f], g [g], gw [g͡w], h [h], j [ʤ̊], k [k], kw [k͡w], nng [ŋː], l [l], m [m], n [n], ñ [ŋ], p [p], qu [k͡w], r [ɾ/r], s [s], t [t], ti [ʧi], ts [ʤ̊], v [f/v], w [w/ɣ], x [k͡s], y [j/ʝ], z [z].