The chapter discusses the various factors influencing the sound absorption characteristics of the acoustical materials. The methodology of testing the sound absorption characteristics in the reverberation chamber as per the ISO 354 method is described. The study also discusses the effect of perforation, air gap, density, and thickness of the absorptive material on the sound absorption characteristics of acoustical materials. The chapter also tabulates the large database of sound absorption characteristics of acoustical materials tested in the reverberation chamber as per ISO 354 method to provide insight and understanding to the researchers and engineers about the Sound Absorption Characteristics (SAC) of various acoustical materials. The study shall provide valuable data for architects, engineers, and designers to select appropriate materials for noise control and shall be helpful in the design and development of acoustical materials of enhanced sound absorption characteristics for noise control applications and acoustic comfort in various environments such as offices, auditoriums, classrooms, theaters, convention halls, and industrial spaces.