Vowel harmony means that a non-compound word contains either back vowels (a, o, u) or front vowels (ä, ö, y), but the vowels e and i (though phonetically front vowels) are neutral in the sense that they may appear with both back and front vowels. For this harmony, any suffix with a back vowel in it has a variant with a front vowel. If the base word contains only the neutral vowels e and i, the suffix has a front vowel.
Thus, any suffix with a, o, or u has a variant with ä, ö, or y, respectively. Examples: talo : talossa – kylä : kylässä (the inessive suffix ssA); sanoa : sanonut – kysyä : kysynyt (the past tense participle suffix nUt), yksi : yksiö – kaksi : kaksio (the word derivation suffix O).
In this book, we use the capital letters A, O, and U as above, to refer to a vowel in a suffix so that A is realized as a or ä, O is realized as o or ö, and U is realized as u or y, depending on vowel harmony. This notation is generally used in modern descriptions of Finnish.
The Finnish vowels can be schematically presented as follows:
|
Front |
Neutral |
Back |
|
y |
i |
u |
|
ö |
e |
o |
|
ä |
|
a |
Thus, the dots in ä and ö indicate them as front vowel counterparts of a and o. It would be logical to use ü rather than y for the front vowel counterpart of u (as Estonian does), but the Finnish alphabet was adopted from Swedish, which does not use ü.
Although the vowels e and i are treated as neutral with respect to vowel harmony, their quality depends on the type of the word, but this is not expressed in writing. For example, the e in kerä (clew) is somewhat different from the e in kera (with), where it is closer to a back vowel.
In a compound word, the last part determines the vowels of suffixes. For example, kesäaika, a compound of kesä (summer) and aika (time) has back vowels in suffixes, as in kesäaikana.
This means that vowel harmony does not apply to a compound word as a whole.
New loanwords and foreign words may contain a mix of front and back vowels, without being compounds. They are handled differently, e.g. analyysi : analyysissa ∼ analyysissä. The recommendation is that the last non-neutral vowel is decisive, unless it is y and there is an a, o, or u earlier in the word. Thus, analyysissa is recommended (though analyysissä is common, too), but we write miljonääri : miljonäärillä, for example.
In foreign names, “visual vowel harmony” is usually applied: the suffixes are selected as if the word were read as is written. This explains inflection like Mary : Marylla, even though the pronunciation of Mary in Finnish is normally [meəri] or [meri] and the suffix lla is here pronounced llä. Such inflection is allowed and even preferred by the language norms. Pronunciation-based writing like Maryllä is allowed as an alternative, but less common.
Loanwords that have four syllables or more are often inflected as if they were compounds, even though they are not compounds in Finnish or even in the original language. Such a tendency is strongest in words like barometri : barometria ∼ barometriä, since it looks like a compound due to may other words ending with metri. The phenomenon may also affect words like karamelli : karamellia ∼ karamelliä that are not compounds in any sense.
There are a few other exceptions to vowel harmony: