Voice onset time in speech to infants and adults
Phonetica 56 (1999):
186 - 199
Investigations of the phonetics of infant-directed speech (IDS) have mainly focused on prosodic aspects, showing extreme values or overspecifications in comparison to adult-directed speech (ADS). On the other hand, studies of segmental properties, especially consonantal ones, are very rare. The lack of knowledge of phonetic characteristics of the infant's speech input is problematic, considering that the infant's perceptual development seems to be attuned towards properties in the ambient language, as suggested by infant perception experiments. In the present study voice onset time (VOT) was measured in Swedish mothers' IDS and in their ADS, VOT was significantly shorter in IDS than in ADS in both voiced and voiceless stops. The impact of stress was very clear in both IDS and ADS, showing significantly longer VOT in stressed positions as compared to the unstressed. The results are discussed in a framework assuming a differential weighting system of different phonetic aspects such as prosodic, consonantal and vocalic, as a function of infant development.