Outdoor-to-indoor sound propagation models for noise exposure studies. New metrics for outdoor and indoor noise exposure related to mental health

Level of evidence	Suggestive evidence, literature reviews, evidence based on theory and linked conceptual models.
Approach	Propagation models are based on measurements at 49 locations in the UK (dwellings) in Greater London and one location in Eindhoven.
Findings	Most studies on noise exposure and health outcomes use outdoor noise levels (derived from noise maps), rather than indoor levels, where children spend most of their time. We developed sound propagation models for indoor noise levels from outdoor sources to better reflect children’s actual noise exposure, based on: ·      Noise levels in indoor and outdoor environments with varied building façade characteristics. ·       Simulations of sound propagation through different types of building façades (structural components). We also characterized environmental sound at home in a manner relevant to the mental health, well-being, and cognitive development of children using: ·      Tailored metrics for road traffic noise to improve the prediction of certain mental health outcomes, including SDQ, KINDL, cognitive development, and attention.
Recommendations	For researchers: ·      Use Equal-Life’s insights into the effects of noise exposure, novel metrics, and software for their efficient calculation, to further investigate impacts of noise exposure on child health and development.
Target audience	Researchers, policy makers, urban planners
Sources	M.E.Terzakis, M.Hornikx, (2025) An outdoor-to-indoor sound propagation modelling framework for evaluating noise exposure applications. Acta Acustica [accepted] https://acta-acustica.edpsciences.org/articles/aacus/full_html/2025/01/aacus250070/aacus250070.html D3.6. New noise metrics for mental health. A report and open-source code on data-driven and hybrid models for new metrics for outdoor and indoor noise exposure related to mental health Dick Botteldooren et al. 2024. https://zenodo.org/records/17432596 Arnaud Can, Dick Botteldooren, Timothy Van Renterghem, Peter Lercher, Rik Bogers (2025) Towards Valid, Transparent and Applicable Noise Indicators for Assessing Early-Life Mental Health Impacts. In preparation. Dick Botteldooren, Lucas Fourneau, Colin Vergaerde, Valentin Le Bescond, Luc Dekoninck, Arnaud Can, Timothy Van Renterghem (2025) A Surrogate Model for Estimating a Wide Range of Traffic Noise Indicators. In preparation.