Assessment of acoustic metawindow unit through psychoacoustic analysis and human perception

Acoustic metamaterials (AMMs) have become so far a resourceful solution for standard materials’ physical limitations, and their tuneable acoustic properties have shown potential for noise reduction and absorption over standard materials. At the same time, the building's features’ ergonomics value has been discovered to play a key role in indoor well-being. So AMM-based design features, such as windows, should be not only assessed through physical parameters (SPL, IL, and TL) but also investigated by psychoacoustics and human perception. Therefore, the methodology presented in this paper has been developed by firstly measuring and recording a previously developed acoustic metawindow (AMW) unit effect over seven environmental sound recordings, and secondly, merging soundscape-based questionnaires (performed in laboratory and online) and analytical physical and psychoacoustic assessment of the AMW unit. A significant quantitative impact on Loudness, Roughness, and Sharpness was achieved through the AMW unit (between 1 and 15.58 times the just noticeable difference of each psychoacoustic parameter). Moreover, participants qualitatively perceived an effect of neutralisation over the seven sound recordings with the AMW unit effect. After pondering the soundscape rates of the environmental recordings with and without the AMW unit effect separately, a percentage comparison highlighted that the first resulted as 7% less chaotic than the second one, 8% less eventful, 9% less vibrant, 23% more monotonous, and 22% more uneventful. In addition, sound sources related to middle-high frequency resulted specifically neutralised. Finally, Loudness was reduced by the AMW unit effect for the same environmental noise recordings in both the quantitative (psychoacoustic parameters) and qualitative (soundscape descriptors) methods. This research could be the first step toward a tuneable AMMs-based window design from physical, psychoacoustic and human perception points of view, creating a new paradigm for natural ventilation/heating control combined with noise reduction systems.