Every day, billions of disposable face masks are either incinerated or discarded, damaging the natural landscape and accelerating environmental pollution. In this study, a sound-absorbing building material was constructed by combining an oak cross-section with disposable mask waste (DMW), and its performance was evaluated. The optimal sound absorption was achieved by combining an oak cross-section with a thickness of 10 mm, an air back cavity with a thickness of 30 mm, and a DMW with a thickness of 10 mm. The maximum absorption peak of this material was 0.72 at 552 Hz, and the noise reduction coefficient (NRC) was measured as 0.49. These results correspond to a 0.5 M grade in the sound absorption rating evaluation according to the KS F 3503 standard. The hybrid material exhibited comparable sound absorption performance to various forest by-products and wood cross-sectional sound absorbers previously investigated by the authors.