Hand-made sound absorber using familiar materials for nursery facilities

We have been proposing a hand-made sound absorber using familiar materials to develop a comfortable sound environment for children. By installing the hand-made absorber, anyone can easily add sound absorption to nursery rooms. In this study, as one of the familiar materials, we focused on bubble wrap, which is used as a packaging material. We measured the normal incidence absorption coefficient of bubble wrap arranged in layers and found that bubble wrap had reasonable sound absorption. As an example of a hand-made absorber, we created round-shaped fabric balls filling bubble wrap and measured the sound absorption performance in a reverberation room. As a result, the fabric ball absorber had sufficiently high sound absorption performance. Additionally, we clarified the sound absorption mechanism of bubble wrap by predicting based on simple assumptions. Therefore, it could be possible to design sound absorbers with higher sound absorption performance at low frequencies by stacking bubble wrap horizontally or vertically.