Hygrothermal treated paulownia hardwood reveals enhanced sound absorption coefficient: An effective and facile approach

•The effect of steam is seen on wood cell walls of paulownia hardwood.•The gas permeability is caused by cellulose crystallinity.•Improved sound absorption properties are observed at 2000 Hz (~81.8%).•This inexpensive method could be useful for manufacturing sound-absorption boards. Hygrothermal treatment is an important and eco-friendly process for softening and improving the quality of wood. Paulownia (Paulownia coreana) hardwood species mostly used to design household furniture, musical instruments, plywood and particleboard. The effect of hygrothermal on the wood cell walls has studied extensively in recent years. However, the relationship between sound absorption coefficient (SAC) and alteration of the cellulose/hemicellulose cell walls of hardwood species are scarcely found. Here, hygrothermal effect with varying temperature (90–120 °C about 2 h) are studied, confirmed by extensive characterization techniques, and results of SAC are reported. Hygrothermal treated paulownia at 110 °C exhibits improved SAC ~ 81.8% (from 0.1115 to 0.2028) at 2000 Hz compared to the untreated paulownia. The enhancement of SAC in an average is 47.42% in a wide range of frequency (2000 Hz–6400 Hz) has been observed. The hygrothermal treated paulownia hardwood can be useful to manufacture sound-absorption board for healthy housing environment.