A language is said to possess consonant harmony when it has a phonological rule requiring some types of consonants in a word to belong to the same class. This kind of harmony may be thought of as a special, regular kind of assimilation.
Examples
Most commonly, consonant harmony requires all the sibilants of the word to belong either to the anterior class (s-like sounds) or the nonanterior class (sh-like sounds). Such patterns are found in Navajo, Kinyarwanda, and elsewhere.
Various Austronesian languages exhibit consonant harmony among the liquid consonants, with [r] assimilating at a distance to [l] or vice versa. Likewise, in Sanskrit, [n] is retroflexed to [ṇ] if certain consonants precede it in the same word, even at a distance.
Guaraní shows nasal harmony, by which certain affixes have alternative forms according to whether the root includes a nasal consonant or not.
Dissimilation
It is to be mentioned that the opposite of consonant harmony, ie., dissimilation, is much more widespread among languages. For example, in Latin, from medidies (the middle of the day, ie. noon) became meridies, so the consonants should differ and thus the word can be pronounced more easily.
In vowel harmony, the place of articulation of the (main) vowel in the root requires that the other vowels (in inflectional and derivational affixes) be adjusted to match it.
Non-initially, the neutral vowels are transparent to and unaffected by vowel harmony.
Kazakh 's system of vowel harmony is primarily a front/back system, but there is also a system of rounding harmony that is not represented by the orthography, which strongly resembles the system in Kyrgyz.
A language is said to possess consonantharmony when it has a phonological rule requiring some types of consonants in a word to belong to the same class.
This kind of harmony may be thought of as a special, regular kind of assimilation.
Various Austronesian languages exhibit consonantharmony among the liquid consonants, with [r] assimilating at a distance to [l] or vice versa.