Manfred R. Schroeder’s life in acoustics: Phases, reflections, and other contributions of a ‘‘perfect number.’’ Free

Number theory such as the rules to compose a perfect number (which is the sum of all its divisors, e.g., 6, 28, 496, 8128) constitutes only a small part of the many fields of research Manfred R. Schroeder mastered in his scientific life. After finishing his Ph.D. with Erwin Meyer in Goettingen in 1954, Schroeder joined Bell Labs where he eventually became director of acoustics and mechanics research. In 1969 he was also appointed professor of physics and director of the Drittes Physikalisches Institut in Goettingen. He contributed to many seminal publications and inventions in the areas of room acoustics, speech coding, physiological and psychological acoustics, and computer graphics. The Schroeder phases describe the quadratic initial phase relation of the harmonics in a tone complex to produce a maximum flat (speech) waveform. The Schroeder diffusors are reflection gratings based on his number theoretic considerations that suppress the specular reflections while distributing scattered sound into all different directions. The current talk will give an overview of Manfred Schroeder’s life in acoustics and his various contributions, including some stories about his unique character. A special focus will be placed on the Schroeder phases and their current use in hearing research.