Characterization, modeling and prediction of foam-formed softwood fiber sound absorption

The transition towards building materials with low or negative carbon-dioxide footprint is a pressing topic in nowadays society. Materials for thermal and acoustic insulation are among those attracting a growing number of research publications. Commonly used materials in the building sector are mostly mineral wools which demand huge amounts of energy during production by melting sand or stone. Cellulose-based materials are a promising substitute for the current market leaders. These materials are able to reach negative carbon footprints due to low embodied energy and their ability to store carbon dioxide in buildings for decades. Predicting the sound absorption behavior prior to manufacturing can further improve their usability. This study delves into the prediction and characterization of wood-based pulp fiber foams and their acoustic properties. By comparing analytical models, semi-phenomenological models and experimental measurements the prediction of sound absorption based on fiber diameter and bulk density is evaluated. The findings reveal that refining a recent analytical model for natural fibers through parameter fitting to non-acoustic parameters yields improved accuracy in predicting sound absorption curves. While the accuracy declines towards higher densities, this work lays the groundwork to create environmentally sustainable sound absorbers with carefully tailored sound absorption properties.