Ulla Sundberg

Voice Onset Time in Speech to Infants and Adults

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.

Linguistic strategies in the first 6 months of life

The ability to detect word contrasts embedded in natural sentences was studied with 62 Swedish infants whose ages ranged from 48 to 147 days, using the high‐amplitude sucking (HAS) technique. The infants listened to one of four possible pairs of natural carrier sentences, produced as child‐directed speech, in which a target word was inserted: (1) a pair of sentences in which the contrasting target words was inserted in focal position; (2) a pair of sentences in which the target words were out of the sentence focus; (3) a pair of sentences that differed only in the position of the sentence focus; and (4) a control pair with two identical sentences. When this group of subjects is divided into two age groups, one below and the other above the median age for all the subjects, a pattern of interaction between the age groups and the experimental conditions is observed suggesting that word discrimination capacity in the younger infants may be disrupted by dominantF 0 variations. For the older group, a tendency t...

An echological theory of language learning

An ecological theory of language acquisition (ETLA), attempting to account for the linguistic development during about the first 18 months of age, is proposed in this contribution. The theory does not assume that the infant is endowed with specialized linguistic devices or strategies at the onset of life. ETLA considers instead the multi‐sensory aspects of the adult‐infant interaction and the typical ecological setting of that interaction. Rather than focusing on the speech signal per se, ETLA considers the infant’s multi‐sensory exposure to the phonetic, prosodic, syntactic and semantic characteristics along with visual, tactile, olfative and other sensory information as a key to the spontaneous emergence of linguistic structure early in life—a structure implicit in the adults use of the language, and that is partly simplified by the infant’s limited production, perception and representation capacities. A functional model illustrating how such general‐purpose mechanisms interacting with the typical senso...

Phonetic specifications in infant‐directed speech

In contrast to the overspecification of prosodic aspects and the expansion of the vowel space typically observed in infant‐directed speech (IDS), VOT measurements of voiceless stop consonants occurring in Swedish mothers’ speech to their 3‐month‐old infants revealed surprisingly lower values in IDS than in the mothers’ adult‐direct speech (ADS). Since the mothers’ underspecification of consonantal contrasts in early IDS, while at the same time exaggerating prosodic and vocal contrasts, may indicate an adjustment to the phonetic aspects that they perceive to be adequate to the infant’s developmental level, the present study of VOT in IDS towards 12‐month‐olds was carried out in order to determine the age interval within which mothers may start to adopt adult‐like VOT contrasts in their IDS. The VOT measurements from the IDS aimed at their 12‐month‐olds showed instead significantly longer durations than in ADS. It is hypothesized that this age‐dependent use of consonantal specifications in IDS may reflect t...

A preliminary investigation of how prosodic cues may help young infants’ to extract words from natural sentences

This paper presents preliminary results of a study assessing 6‐month‐old infants’ capacity to pick up linguistically relevant information presented in complex naturalistic linguistic contexts. The head‐turn procedure was used to investigate the infants’ ability to discriminate target words that are embedded in natural carrier sentences. The sentences were produced as infant‐directed or adult‐directed speech (‘‘direction’’) and for each direction of the target word occurred either in emphatic or nonemphatic position (‘‘focus’’). A large number of sentences, including all the possible combinations of direction and focus, was first submitted to adult scrutiny in order to select unambiguous carrier sentences in which adequate target words were subsequently edited. Both adults and infants were tested by the head‐turn procedure, to assess the differences between the infants’ and adults’ use of the prosodic information. [Research supported by The Bank of Sweden Tercentenary Foundation, Grant No. 94‐0435.]