2.1 Vowel Harmony and Reduction

Tailaa has the phenomenon called vowel harmony, which restricts the cooccurrence in a word of vowels belonging to different articulatory subgroups. Vowels within a word 'harmonize' to be either all front or all back. It has a tripartite vowel harmony system, with of the nine vowels three being front (i, e, a), three being back (u, o, ɑ), and three being neutral (y, ʊ, ø). All Tailaa roots must have only those in either front or back harmony, neutral vowels able to appear in both back and front harmonizing words. Words with only neutral vowels are back-harmonizing. Tailaa harmony is progressive, thus, when suffixes or compounds are added upon the root, they harmonize with the root, so the second form genitive ending upon front harmonizing word eale 'moon' becomes ealin, while upon back harmonizing word vüsö 'sheep' becomes vüsun.

Along with harmony, vowel reduction is a process where vowels are assimilated or syncoped due to the addition of suffixes. This occurs either:

(1) with an ending beginning with the same consonant as the initial consonant of a preceding CV syllable, causing vowel syncope of the vowel in between, for example mana 'mother' + -ne (Class VI) → manne (under this rule, the word does not take further consonant gradation). This doesn't include trigger in cases like culcyn-ön, as it doesn't fit the criteria above stated.

(2) with an ending that closes a previously open syllable, or an ending beginning with a cluster reduces the vowel, weakening the vowel between, for example halaa 'wind' + -nn (class II) → halann. Endings with clusters and geminates count as closing the syllable. This weakening shortens long vowels, reduces diphthongs to long monophthongs of the initial element, and causes short vowels to assimilate to the preceding segment. For the diphthongs /ea, ei, oä, ou/, which begin on an unlengthenable vowel, they become /ie/ and /uo/ respectively.

2.2 Consonant Gradation

Following vowel weakening, consonant gradation is triggered when morphological processes, primarily suffixation, place a strong consonant in a prosodically weak position. This typically occurs either:

(1) when a strong consonant is placed in the onset of a word-medial syllable following an open syllable (e.g., veinta 'mountain' + -vai (superessive case) → veintauai, with /ʋ/ gradating to /w/), or

(2) when resyllabification caused by an ending opens a previously closed syllable, gradating the syllable initial (e.g., äumuor 'travail, cost' + -oä (Class I suffix) → äuvuoroä, with /m/ in the root gradating to /ʋ/).

Aside from straightforward quality-based lenition, Tailaa also sees the simplification of clusters. Doubled consonants are shortened when weakened, for example halaa 'wind' + -llü (elative case) → halalü, and when a cluster is placed in a position that undergoes gradation, it becomes a geminated form of the initial consonant, if that consonant is geminable, for example preille 'flower' + -mpen (collective derivation) → preillimmen 'bouquet of flowers', culcyn 'wolf' + -uol (benefactive case) → cullynuol. For ungeminable sounds, the second of a cluster simply drops. /j/ isn't included in gradation as /j/ in that context is viewed as an off-glide, thus össiär 'circular, smooth' with -ulö (adverb) → ösiärulö 'smoothly', with the geminated /s/ gradating but leaving /j/ untouched.

2.3 Epenthesis and Other Changes

Finally, epenthesis occurs to fix illegal sequences. If a morphological process creates an illegal consonant cluster, an epenthetic vowel is inserted. The vowel chosen is the nearest preceding vowel. Secondly, similar to intrusive iuliä (cf. 1 Phonology § 1.5 Sandhi) If more than three vowels occur in sequence, or an illegal diphthong is formed, an epenthetic consonant is inserted: /j/ in front harmony contexts and /ʋ/ in back harmony contexts. If two identical sounds become adjacent through morphology, they lengthen. These changes generally do not apply to compound words.

Finally, sequences formed that have /i/ and /j/ adjacent merge to one /j/, or /i̯/ word final. Thus, tisiel 'to invoke'+ -en (progressive aspect) → *tijelen with /ç/ gradating to /j/, and *tijelen with illegal sequence /ij/ becomes tielen 'to be invoking' with /ij/ merging. Likewise /w/ adjacent to /u/ or /ʊ/ merge to one /w/, or /u̯/ word final when gradation creates /w/ next to them. Thus, väldu 'husband' + -vo (comitative case) → *välduwo with /ʋ/ gradating to /w/, and *välduwo with illegal sequence /uw/ becomes välduo 'with [a] husband' with /uw/ merging. Finally, /ʎ/ and /ç/ simplify to /l/ and /x/ when /i/ is placed adjacent, for example ilie + -nn → *iljinn → ilinn.