Finnish vowel harmony rules require that if the vowel in the first syl
lable of a word belongs to one of two vowel sets, then all subsequent
vowels in that word must belong either to the same set or to a neutral
set. A harmony mismatch between two syllables containing vowels from
the opposing sets thus signals a likely word boundary. We report five
experiments showing that Finnish listeners can exploit this informatio
n in an on-line speech segmentation task. Listeners found it easier to
detect words like hymy at the end of the nonsense string puhymy (wher
e there is a harmony mismatch between the first two syllables) than in
the string phyhymy (where there is no mismatch). There was no such ef
fect, however, when the target words appeared at the beginning of the
nonsense string (e.g., hymypu vs hymypy). Stronger harmony effects wer
e found for targets containing front harmony vowels (e.g., hymy) than
for targets containing back harmony vowels (e.g., pale in kypalo and k
upalo). The same pattern of results appeared whether target position w
ithin the string was predictable or unpredictable. Harmony mismatch th
us appears to provide a useful segmentation cue for the detection of w
ord onsets in Finnish speech. (C) 1997 Academic Press.