Traditional sound-absorbing materials have a number of disadvantages: low water resistance, low compressive and tensile strengths, low weather resistance, etc. Therefore, new sound-absorbing materials need to be developed with improved properties including the involvement of industrial byproducts. The influence of the grain-size composition of the rubber crumb from used car tires on the sound insulation of cement and gypsum composites was studied in the paper. The results of the study contribute to the creation of a structural material for the manufacture of sound-absorbing as well as load-bearing structures. The field of application of the developed materials is very extensive.