Syllable Structure

(C)CV(C(C)) or (C)CVV(C), where CC and VV may or may not be long consonants and vowels respectively.

Note that long consonants cannot be realized at the end of a word, and if a situation arises where a long consonant does fall at the end of a word, it will be realized as a short consonant.

Phonemes

Consonants

Plosives: /p t k/ <p t k>
Affricates: /ts tɕ/ <c ć> (These have both short and long versions, the long versions being held longer before release.)
Voiced fricatives: /β ð ɣ/ <b d g> (These are never long.)
Voiceless fricatives: /s ɕ x/ <s ś h>
Nasals: /m n ɲ/ <m n ń>
Laterals: /l ʎ/ <l ĺ>
Trills: /r/ <r>
Semivowels: /w j/ <w j> (These are never long.)

Vowels

Short monophthongs

Close: /i y u/ <i y u>
Close-mid: /e o/ <é ó>
Open-mid: /ɛ œ ɔ/ <e ø o>
Open: /a ɒ/ <a å>

Oral long monophthongs

Close: /iː yː uː/ <ii yy uu>
Open-mid: /ɛː œː ɔː/ <ee øø oo>
Open: /ɑː/ <aa>

Nasal long monophthongs

Near-close: /ɪ̃ː ʏ̃ː ʊ̃ː/ <in yn un>
Open-mid: /œ̃ː/ <øn>
Near-open: /æ̃ː/ <en>
Open: /ɑ̃ː ɒ̃ː/ <an on>

(These reflect former vowel-short coda nasal sequences, with neutralization of vowel length, and with subsequent changes in vowel quality not reflected by the orthography. Note that long nasals between vowels were not affected)

Diphthongs

Opening: /iə̯ yə̯ uə̯/ <ie ye ue>
Closing: /ɛi̯ œy̯ ɔu̯/ <ei øy ou>

Allophony

The phonology specified so far is in many ways pretty transparent, but there are still some allophonic rules at work:

/β ð/ are realized as [b d] before and after nasals and laterals.
/ɣ/ is realized as [g] before and after non-palatal nasals and laterals and [ɟ] before and after palatal nasals and laterals.
/β ð ɣ/ are realized as [ɸ θ x] before or after voiceless obstruents except in markedly careful speech.
/ɣ/ is realized as [ʝ] before /j/.
/w j/ undergo fortition to behave as if they were /β ɣ/ when not followed by a vowel.
/æ̃ː œ̃ː ɪ̃ː ʏ̃ː ɑ̃ː ɒ̃ː ʊ̃ː/ when followed by a vowel become [ɛn œn in yn an ɔn un].
Intervocalic /r/ is realized as [ɾ]; /r/ in other positions is realized as [r], and /rː/ is always realized as [rː].

Some phonological background

The current vowel system is descended from one that historically had a full set of short close-mid vowels, /e ø o/, and a set of long close-mid vowels, /eː øː oː/, as well.

/ø/ irregularly merged in the present vowel system with both /œ/ and /y/. /eː oː/ diphthongized and were raised regularly to form /iə̯ uə̯/ in the present vowel system. /øː/ generally was diphthongized and raised to form /yə̯/ in the present vowel system, but sometimes was lowered to form /œː/ in the present vowel system instead.

Present /xpː xtː xkː xtːs xtːɕ βm ðn ɣɲ ðl ɣʎ/ are generally derived from the past overlong consonants /pːː tːː kːː tːːs tːːɕ mːː nːː ɲːː lːː ʎːː/. However, there may be exceptions, where such consonant clusters already existed before the breaking of said overlong consonants.