Distinguishing infant-directed speech and songs: The distinctive evolution of acoustic features and visual entrainment in infants

Project Information

MusicalSpeech

Grant agreement ID: 101149355

DOI

10.3030/101149355

EC signature date 14 March 2024

Start date 1 April 2024

End date 31 March 2027

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 252 724,32

Coordinated by

UNIVERSIDAD DE GRANADA
Spain

Periodic Reporting for period 1 - MusicalSpeech (Distinguishing infant-directed speech and songs: The distinctive evolution of acoustic features and visual entrainment in infants)

Reporting period: 2024-04-01 to 2026-03-31

Summary of the context and overall objectives of the project

Given the immature cognitive abilities of infants at birth, caregivers connect with them by producing stereotyped infant-directed (ID) forms of speech and songs in which the acoustic features are modified. Although ID vocalisations are fundamental for establishing social and affective bonds, key aspects of infant–caregiver interactions are still poorly understood. One of the goals of the Musical Speech project is to identify distinctive acoustic adaptations of ID speech and songs to cross-culture recordings from diverse societies, and track the evolution of those acoustic markers over the first year of life. In addition, recent evidence shows that the rhythm of ID singing acts as an effective cue for infants to attend to emotionally and socially-relevant content, such that infants look more to the caregiver’s eyes during on-beat moments of the songs. This project aims to determine whether rhythm in ID speaking similarly attunes infants’ attention and whether ID speech elicits distinctive patterns of attention before and after 6 months (as it serves more of a linguistic purpose). Using audiovisual recordings of adults speaking/singing to infants, this project will implement cutting-edge eye-tracking measures to samples of Canadian and Spanish infants. Finally, prematurity and individual differences in neural coding of rhythm, measured with a state-of-the-art EEG paradigm, can affect early interactions. Thus, the eye-tracking outcomes of terms and an additional sample of preterms will be correlated with the EEG signal elicited by rhythmic stimuli. The cross-laboratory studies proposed in this innovative project will comprise training on advanced statistical techniques and leadership, as they rely on the coordination of an international network. The project can contribute to basic and applied fields with unprecedented, high-quality insights and an experimental paradigm shift to compare early language and music perception.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project has been implemented in line with the objectives and timeline described in the Description of Action, with all core work packages reaching an advanced or completed stage.

Study 1 (WP1)
This study examined how caregivers’ acoustic properties in infant-directed (ID) speech and singing vary as a function of infants’ age across the first year of life. The work included dataset curation, extraction of spectro-temporal modulation (STM) features and related acoustic descriptors, and the application of statistical models to characterize developmental trajectories. Data preprocessing and primary analyses have been completed.

Study 2 (WP2 & WP3)
This study investigated how auditory and visual rhythmic cues of ID speech and singing shape the temporal dynamics of infant attention. The work involved the creation of audiovisual stimuli (including experimentally manipulated conditions isolating auditory and visual rhythms), development and validation of the experimental task, infant eye-tracking data collection, preprocessing of multimodal data (gaze, motion, and acoustic features), and implementation of time-resolved and model-based analyses (e.g. permutation-based approaches and temporal response function models). Data collection and primary analyses for a substantial portion of the sample have been completed.
Across both studies, the project also included dissemination activities, open science practices (e.g. preregistration, sharing of materials), and manuscript preparation.

Main achievements
- Sensitivity of spectro-temporal modulation (STM) to communicative context and development.
The project demonstrates that STM reliably captures differences between ID speech and singing, and is sensitive to subtle, continuous age-related changes in how caregivers structure these interactions across the first year of life.

- Complementary roles of auditory and visual rhythms in shaping infant attention.
The project shows that auditory and visual rhythmic cues make dissociable contributions to attentional dynamics: visual cues act as a robust driver of phase alignment, whereas auditory rhythms modulate the temporal structure of that alignment.

- Evidence for flexible, cross-modal temporal tuning.
When both modalities are present, infants adjust the tempo of their attentional alignment to match faster, hierarchically nested auditory rhythms, indicating sensitivity to cross-modal temporal structure.

- Integration of naturalistic and experimental approaches.
The project successfully combines ecologically valid stimuli with controlled manipulations of modality-specific information, enabling causal inference about the role of rhythmic cues.

- Methodological advancement in time-resolved analysis of attention.
The use of event-based analyses, permutation testing, and temporal response function modelling provides a robust framework for quantifying attention in dynamic social contexts.

- Commitment to open and reproducible science.
Preregistration, sharing of materials and data, and transparent analytical pipelines enhance reproducibility and reuse.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project advances the state of the art by demonstrating that early caregiver–infant communication is a multimodal, temporally structured system in which auditory and visual cues play complementary roles. Specifically, STM captures both differences between infant-directed speech and singing and subtle developmental changes across the first year, while auditory and visual rhythms differentially shape infant attention (visual cues driving phase alignment; auditory cues modulating temporal structure).

- Scientific impact: Contributes to the theoretical understanding of early communication and attention by showing that infants’ attentional dynamics are governed by dissociable yet interacting cross-modal rhythmic mechanisms, rather than by unimodal or undifferentiated audiovisual input.
- Societal impact: Provides evidence supporting the importance of coordinated speech, movement, and singing in caregiver–infant interaction, informing parenting practices and early childhood development strategies.
- Socio-economic relevance: Offers a foundation for low-cost, scalable interventions (e.g. rhythm- and music-based approaches) to support attention and learning in early development, including in at-risk populations.

MusicalSpeech: Methodology & Findings