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Vowel hypo-and hyperarticulation (VHH) was investigated in Swedish infant-directed speech (IDS) to Swedish 12-month-olds using a measure that normalizes across speakers and vowels: the vhh-index. The vhh-index gives the degree of VHH for each individual vowel token, which allows for analysis of the dynamics of VHH within a conversation. Using both the vhh-index and traditional measures of VHH, the degree of VHH was compared between Swedish IDS and ADS. The vowel space area was larger in IDS than in ADS, and the average vhh-index as well as the modal value was higher in IDS than in ADS. Further, the proportion of vowel tokens that were highly hyperarticulated (vhh-index > 75th percentile) were fewer in ADS than in IDS. Vowels in Swedish IDS to 12-month-olds are thus concluded to be hyperarticulated compared to vowels in Swedish ADS, both in terms of degree and frequency. Findings are in line with previous reports on VHH in Swedish IDS as well as on VHH in IDS to infants around 12 months in other languages. The study considers the importance of robust formant estimation, highlights the need for replication of studies on VHH in IDS on previously studied languages and ages, and discusses the benefits of the vhh-index. Those benefits include that it normalizes across speakers and vowels, can be used for dynamic measures within speech samples, and permits analyses on token-level.

The amplitude of the event-related N1 wave decreases with repeated stimulation. This repetition-attenuation has not previously been investigated in response to variable auditory stimuli, nor has the relative impact of acoustic vs. perceptual category repetition been studied. In the present study, N1 repetition-attenuation was investigated for speech and spectrally rotated speech with varying degrees of acoustic and perceptual category variation. In the speech condition, participants (n = 19) listened to stimulus trains consisting of either the same vowel exemplar (no variability condition), different exemplars of the same vowel (low variability condition), or different exemplars of two different vowels (high variability condition). In the rotated speech condition, the spectrally rotated counterparts of the vowels were presented. Findings show N1 repetition-attenuation in the face of acoustic and perceptual category variability, but no impact of the degree of variability on the degree of N1 attenuation. Speech stimuli resulted in less attenuation than the acoustically matched non-speech stimuli, which is in line with previous findings. It remains unclear if the attenuation of the N1 wave is reduced as a result of stimuli being perceived as belonging to perceptual categories or as a result of some other characteristic of speech.

Parental responsive behaviour in communication has a positive effect on child speech and language development. Absence of canonical babbling (CB) in 10-month-old infants is considered a risk factor for developmental difficulties, yet little is known about parental responsiveness in this group of children. The purpose of the current study was to examine proportion and type of parental responsive utterances after CB and vocalization utterances respectively in a clinical group of children with otitis media with effusion, with or without cleft palate. Audio-video recordings of interactions in free play situations with 22 parents and their 10-monthold infants were used, where 15 infants had reached the CB stage and 7 infants had not. Fifty consecutive child utterances were annotated and categorized as vocalization utterance or CB utterance. The parent's following contingent response was annotated and labelled as acknowledgements, follow-in comments, imitations/expansions or directives. The Average intra-judge agreement was 90%, and the average interjudger agreement was 84%. There was no significant difference in proportion contingent responses after vocalizations and CB, neither when considering all child utterances nor the child's babbling stage. However, imitations/expansions tended to be more common after CB in the typical babbling group, whereas acknowledgements were more common after CB in the late babbling group. Our findings imply that responsiveness is a supportive strategy that is not fully used by parents of children with late babbling. Implications for further research as well as parent-directed intervention for children in clinical groups with late babbling are suggested.

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Abstract-When adults talk to infants they do that in a different way compared to how they communicate with other adults. This kind of Infant Directed Speech (IDS) typically highlights target words using focal stress and utterance final position. Also, speech directed to infants often refers to objects, people and events in the world surrounding the infant. Because of this, the sound sequences the infant hears are very likely to co-occur with actual objects or events in the infant's visual field. In this work we present a model that is able to learn wordlike structures from multimodal information sources without any pre-programmed linguistic knowlege, by taking advantage of the characteristics of IDS. The model is implemented on a humanoid robot platform and is able to extract wordlike patterns and associating these to objects in the visual surrounding.

Extreme or exaggerated articulation of vowels, or vowel hyperarticulation, is a characteristic commonly found in infant-directed speech (IDS). High degrees of vowel hyperarticulation in parent IDS has been tied to better speech sound category development and bigger vocabulary size in infants. In the present study, the relationship between vowel hyperarticulation in Swedish IDS to 12-month-old and phonetic complexity of infant vocalizations is investigated. Articulatory adaptation toward hyperarticulation is quantified as difference in vowel space area between IDS and adult-directed speech (ADS). Phonetic complexity is estimated using the Word Complexity Measure for Swedish (WCM-SE). The results show that vowels in IDS was more hyperarticulated than vowels in ADS, and that parents’ articulatory adaptation in terms of hyperarticulation correlates with phonetic complexity of infant vocalizations. This can be explained either by the parents’ articulatory behavior impacting the infants’ vocalization behavior, the infants’ social and communicative cues eliciting hyperarticulation in the parents’ speech, or the two variables being impacted by a third, underlying variable such as parents’ general communicative adaptiveness.

When speaking to infants, parents typically use infant-directed speech, a speech register that in several aspects differs from that directed to adults. Vowel hyperarticulation, that is, extreme articulation of vowels, is one characteristic sometimes found in infant-directed speech, and it has been suggested that there exists a relationship between how much vowel hyperarticulation parents use when speaking to their infant and infant language development. In this study, the relationship between parent vowel hyperarticulation and phonetic complexity of infant vocalizations is investigated. Previous research has shown that on the level of subject means, a positive correlational relationship exists. However, the previous findings do not provide information about the directionality of that relationship. In this study the relationship is investigated on a conversational turn level, which makes it possible to draw conclusions on whether the behavior of the infant is impacting the parent, the behavior of the parent is impacting the infant, or both. Parent vowel hyperarticulation was quantified using the vhh-index, a measure that allows vowel hyperarticulation to be estimated for individual vowel tokens. Phonetic complexity of infant vocalizations was calculated using the Word Complexity Measure for Swedish. Findings were unexpected in that a negative relationship was found between parent vowel hyperarticulation and phonetic complexity of the immediately following infant vocalization. Directionality was suggested by the fact that no such relationship was found between infant phonetic complexity and vowel hyperarticulation of the immediately following parent utterance. A potential explanation for these results is that high degrees of vowel hyperarticulation either provide, or co-occur with, large amounts of phonetic and/or linguistic information, which may occupy processing resources to an extent that affects production of the next vocalization.