Professor Dah-You Maa (Ma Dayou), a member (academician) of the Chinese Academy of Sciences (CAS), and a professor at Institute of Acoustics, Chinese Academy of Sciences (IACAS), passed away peacefully in the Beijing Hospital on Tuesday, 17 July, 2012, at his age of 97.

Professor Maa was born in Beijing on March 1st, 1915, obtained his B.Sc. from Peking University in 1936. In 1937, he went to the University of California, Los Angeles (UCLA) and began his graduate studies with Professor Vern O. Knudsen. The following year, when Professor Knudsen was on sabbatical leave, Maa continued his research with Professor Frederick V. Hunt at Harvard University. Within his first two years in the US, Maa’s research resulted in two journal publications: “Distribution of Eigentones in a Rectangular Chamber at Low Frequency Range” as a result of his research with Professor Knudsen, and “Analysis of Sound Decay in Rectangular Rooms,” which he co-authored with Professor Hunt and his fellow classmate, Leo Beranek. Those two publications, published in the Journal of the Acoustical Society of America (JASA) in 1939, established a new chapter in the development of fundamental theories of room acoustics.

Professor Maa got his Master degree in 1939 and then his Ph.D. degree in 1940 at Harvard University. He was awarded the fellowship of Acoustical Society of America (ASA) in 1943. In 2012, Maa was awarded the 19th Honorary Fellow of ASA.

After obtaining his Ph.D. from Harvard University, Maa returned to China and served his country with teaching at National Southwest Associated University in Kunming in those very difficult days during the World War II. In 1946, Professor Maa went back to Peking after the war, and at the age of 31, he founded the Engineering College at Peking University and served as the first Dean of it. In 1956, Professor Maa took part in the formulation of “The national visionary plan for science and technology development between 1956 and 1967” and put forward strong recommendations for an acoustics research center to be established within the Institute of Electronics, Chinese Academy of Sciences (IECAS). He then served as a director for the center for a number of years. Between 1956 and 1958, Professor Maa established the first ever comprehensive acoustic research centre in China which consisted of a number of large-scaled acoustic laboratories including an anechoic chamber, two reverberation rooms, a set of sound insulation measurement chambers and some underwater acoustical laboratories. In 1978, he was appointed the Head of the Physics Department and the Deputy Acting Dean of Graduate School of the Chinese Academy of Sciences, where he worked for seven years. During his lifelong career in education he had taught courses in physics, electronics, electrical engineering, and acoustics.

Professor Maa accomplished remarkable work throughout his career including contributions to speech analysis, synthesis and recognition technology, and theories and experiments in noise control, nonlinear acoustics and infrasonics. Many of his pioneering contributions in research areas such as the theory and application of micro-perforated absorbers (MPA), active noise control in rooms, theory and experiments of high-intensity standing waves, and development of the theory of turbulent jet noise and its control, are all well known to the acousticcommunity. He has received numerous academic honors, national science awards, and prizes for his innovations and advanced contributions to the science and technology research and development. He was elected to the Chinese Academy of Sciences in 1955.

The design and construction of a high intensity sound test facility required sound absorbing material different from the traditional glass fiber or metal gauze mat. Professor Maa conducted many experimental studies and theoretical analyses, and confirmed micro-perforated panels to be durable and effective for high temperatures, high airflow, and high sound intensity. He firstly presented these results at the National Acoustics Meeting in 1973 in Beijing, and published them in Scientia Sinica (in Chinese) in 1975. Further advanced research work was published in journals in China and abroad, such as the Noise Control Engineering Journal (1987), JASA (1998), and International Journal of Acoustics and Vibration (2007). MPA elements are now widely used as green products in buildings and industries in various countries , making them effective alternatives to conventional absorptive materials in critical applications. In one notable example, transparent micro-perforated absorbers were used in the German Parliament Hall in Bonn in 1993, and efficiently solved the existing architectural acoustic problems. Professor Maa is widely known as the father of fiber-free absorbers, and received National Science Congress Award in 1978, the National Natural Science Award in 1981, the First Class Prize of Significant Achievement Science and Technology of CAS in 1985, the Gold Medal from the Fraunhofer Society of Germany in 1997 and Ho Leung Ho Lee Science and Technology Progress Award in 1998, as well as the Prize of National Science and Technology Progress in 2005.

Professor Maa was one of the founding members of the Technical Committee on Acoustics in the Chinese Society of Physics, later to become the Acoustical Society of China (ASC), where he served as president (1982-1985) and honorary president (1985). He was the founder of the IACAS (1964), and also served as Chairman (1980-2007) and later honorary Chairman (2007) of the Chinese National Standardization Technical Committee on Acoustics. He had been the Editor-in-Chief of both ACTA ACUSTICA (in Chinese) since its inception in 1964 and the Chinese Journal of Acoustics (in English) since 1984. Furthermore, Professor Maa was elected as a Member of the New York Academy of Sciences in 1981, and in 1984 he became a Committee Member of the International Union of Pure and Applied Physics, UNESCO. In recognition of his scientific contributions in the field of acoustics all around the world, Professor Maa was awarded the title of Honorary Fellow of the International Institute of Acoustics and Vibration (IIAV) in 2001.

Throughout his academic career, Professor Maa had authored and co-authored more than 20 books and 200 plus papers on scientific researches and engineering education. One of his latest books, “Theoretical Foundation of Modern Acoustics” published in 2004, systematically reflects his deeper understanding of acoustics theory through his own contributions, and discusses new developments of acoustic technology. This book, published when Professor Maa was 89 years old, has been widely used as a text or main reference book in many universities in China. He supervised more than 40 graduate students, a number of whom have established themselves as highly recognized professors and prominent acoustical scientists throughout the world. Two have gone on to become successful Academicians of CAS. Furthermore, many outstanding acousticians in China are his Ph.D. students or advisees.

Professor Maa was devoted to Rong Ho Wang (a physician), his wife of 65 years, and their two children: Xiaofei, who obtained his Ph.D. from the University of Michigan and Xiaobin, who is an associate professor of pharmacy in Beijing. Professor Maa is survived by his wife, their daughter and son.