Acoustic analysis of lexical stress in Greek preschool children

Abstract

Lexical stress carries significant functional load in Greek; there are several pairs and even triplets of words that are differentiated only by stress position. Greek stressed vowels are longer and have a greater amplitude compared to their unstressed counterparts. Lexical stress is also indirectly signalled by pitch movement (Arvaniti, 2007). The trajectory of lexical stress development has received little attention, both in Greek and in the international literature, especially regarding the acoustic analysis of prominence. Therefore, the aim of this study was to investigate the acoustic realisation of stress during Greek acquisition. To that end, 24 typically developing children aged 4;7 to 6;4 (years;months), and 24 adults aged 20 to 25, carried out a word repetition task involving 20 minimal stress pairs (15 real words and five non-words). Duration, intensity and F0 variation, indices of the relative prominence of stressed to unstressed vowels, were calculated. Overall, although the use of the intensity cue for lexical stress did not differ significantly between the two groups, children tended to use the vowel duration cue to a lesser extent than adults to signal lexical stress position. On the other hand, F0 variation indices were significantly higher in the children’s data. Additionally, the acoustic analysis indicated that children utilized the pattern of devoicing unstressed vowels, a specific type of vowel reduction optionally applied in Greek, much more extensively than adults. Finally, although for the most part the word productions carried unequivocal and correct lexical stress, in a few cases children, contrary to adults, had difficulties signalling lexical stress position in a perceptually transparent manner. This study is one of the few attempts to describe the acoustic characteristics of lexical stress in Greek typical development.