This book explores the principles and applications of acoustic absorbers and diffusers, crucial elements in the field of architectural acoustics. It provides a comprehensive overview of the materials, designs, and technologies used to manage sound in various environments, including concert halls, recording studios, and public spaces. The text delves into the science behind sound absorption and diffusion, offering practical insights into measurement techniques and performance evaluation. Illustrated with examples and case studies, it serves as a valuable resource for acousticians, architects, and engineers seeking to enhance sound quality and control noise in their projects.