Assimilation

Assimilation in the general sense means that a sound is changed due to the effect of a nearby sound so that the sounds become more similar or even identical. Vowel harmony can be described as a form of remote assimilation. However, in descriptions of Finnish, assimilation usually means just assimilation of a consonant due to an effect of another consonant after it.

The most common type is assimilation of [n] so that it becomes

• the eng sound [ŋ] before [k] and [g]; this assimilation is not shown in writing, i.e. [ŋk] is written as nk
• the [m] sound before [m], [p], and [b], e.g. olenpa [olempa]
• identical with the next sound when it is [j], [l], [r], [s], or [v] e.g. pojan luo [pojal luo]; these assimilations are not regular; they depend on dialect, speaker, speed of speech, and other factors

Assimilation of [n] is usually not indicated in writing, except inside a primary word. By “primary word”, we mean that word-like suffixes and components of a compound word are regarded as words in this context. Thus, we write onpa [ompa], talonpoika [talompoika], and monenmoinen [monemmoinen]. The assimilation is indicated in the word ompi (poetic variant of on), since pi is an inflection suffix. As an exception, assimlation is also indicated in compound words where the first part is a one-syllable pronoun, e.g. tällainen (tän + lainen) and sellainen (sen + lainen), but e.g. toisenlainen [toisellainen]. The rules are difficult to master even to native speakers, so misspellings are common.

Assimilation of [t] is never indicated in writing; it may occur

• frequently in common spoken language in the participle endings -Ut and in the word nyt; the [t] becomes identical with next consonant, e.g. ollutkaan [ollukkaan]
• often in Western dialects in other word-final positions when the next sound is a stop, e.g. standard miehet kantavat may correspond to [miehek kantaa]; this may also happen before a word-like suffix, e.g. [miehekkin], standard Finnish miehetkin

Other assimilations occur within a word before an inflectional suffix and are described in sections that deal with each inflection form. A typical example is assimilation of the [n] consonant in participle endings -nUt so that it becomes identical with the preceding consonant, e.g. tul- (stem of tulla) + -nUt = tullut. Such assimilations are always indicated in writing, and they can alternative be described just as suffix form variation.