KNUDSEN, VERN OLIVER

(b. Provo, Utah, 27 December 1893; d. Los Angeles, California, 13 May 1974)

physics.

Knudsen was the son of Andrew Knudsen and the former Chesty Sward, who had emigrated from Norway and Sweden, respectively, in the middle of the nineteenth century. They were farmers and members of the Church of Jesus Christ of Latter-Day Saints (Mormon). They raised seven children, of whom Vern was the youngest. As a boy he worked on the family farm until it was decided that because of his interest and success in schoolwork, he should be permitted to attend Brigham Young University in Provo, from which he graduated A.B. in 1915. His first plans were for a career in engineering, but in his later undergraduate years he came under the influence of Harvey Fletcher, who was teaching physics at Brigham Young University at the time. Fletcher persuaded Knudsen to go into physics. After graduation Knudsen served for three years as a Mormon missionary in the Chicago area. It was in connection with his missionary work that he met his wife, Florence Telford. Married in December 1919, they had two sons and two daughters.

Toward the end of World War I, Knudsen joined Fletcher in the research division of the American Telephone and Telegraph Company (which later became the Bell Telephone Laboratories) and pursued military research on electronics.

In 1919 Knudsen entered the graduate school of the University of Chicago, where he studied under Albert A. Michelson, Robert A. Millikan, and Henry G. Gale, For his doctoral research Millikan suggested that Knudsen work on the electron theroy of the specific was based on the study of the sensitivity of the ear to small differences in intensity and frequency. In his dissertation research Knudsen profited greatly from his collaboration with the otologist George E. Shambaugh. The Ph.D. degree was awarded to Knudsen magna cum laude in 1922.

Though offered positions at both the University of Chicago and Bell Laboratories, Knudsen chose to accept an instructorship in physics at what was then called the University of California, Southern Branch (later renamed the University of California at Los Angeles). This institution had only recently been established and provided rather primitive conditions for both teaching and research. However, Knudsen showed great resourcefulness in making do with the available equipment and embarked at once on a research program in architectural acoustics. Here he was much aided by the presence in the Los Angeles area of many auditoriums and assembly rooms, church sanctuaries, and other spaces that badly needed acoustical treatment. He also continued his interest in otology through his association with a distinguished Los Angeles otologist, Dr. Isaac H. Jones. During the period 1922 to 1932 Knudsen published many papers on audition problems in collaboration with Jones. There was also a considerable output of papers on the history of special auditoriums. Much of this was summarized in lectures given in 1930 at the Twelfth International Congress of Architects in Budapest.

Around 1930 Knudsen began to devote attention to the purely physical problems associated with the absorption of sound in the air in rooms, particularly the effect of humidity on this absorption. In his first paper published in the Journal of the Acoustical Society of America (July 1931), Knudsen showed conclusively that the absorption of sound in a room does not take place solely in the materials in the walls, the floor, the ceiling, and the clothing of the audience but also in the air, and depends especially on the humidity of the latter. Through collaboration with the German physicist Hans O.Kneser in Stuttgart, Knudsen’s experimental results were interpreted on the basis of relaxation processes of the molecules of oxygen and nitrogen among themselves as well as with the molecules of water vapor. A paper by Knudsen summarizing his results was presented at a meeting of the American Association for the Advancement of Science in the early 1930’s and was awarded a prize of $1, 000 as the outstanding paper at the meeting.

Knudsen’s interest in this physical side of room acoustics continued for many years and led to the production of ten papers on the acoustical relaxation process in oxygen, nitrogen, and other gases during the period 1931 to 1955.

In the meantime Knudsen consulted on the acoustical renovation and design of auditoriums in the Los Angeles area. This led to the publication in 1932 of his fundamental text Architectural Acoustics, a volume that epitomized both the theoretical side of the subject and the contemporary practical applications, such as radio broadcasting and sound moving pictures. Altogether, some thirty-five professional articles on architectural acoustics were published by Knudsen from 1925 to 1970. He became one of the most sought-after consultants in the field.

Knudsen’s second book, written in collaboration with Cyril Harris, was Acoustical Designing in Architecture (1950). This incorporated the newer developments in room acoustical theory, such as the concept of diffusivity, the role of normal modes in sound production, reverberation control, sound reinforcement, and newer and more accurate absorption coefficients for acoustical materials. The volume, which emphasizes the proper design of rooms and auditoriums, was reprinted in paperback (1973).

As he grew older, Knudsen became increasingly concerned with the problem of noise in human society and was active in movements to control it.

A prime mover in the organization of the Acoustical Society of American in 1929, Knudsen served as its third president (1933–1935). The society honored him with its honorary fellowship in 1954, with the first presentation of the Wallace Clement Sabine Medal in 1957, and with its gold medal in 1967.

Knudsen was responsible for much of the development of the University of California at Los Angeles, not only in the department of physics, of which he was chairman for several years, but also in its general academic program. He successfully promoted graduate studies, becoming the first dean of its graduate school (1954–1958). He was appointed vice-chancellor of UCLA in 1956, and from 1959 to 1960 he was chancellor.

During World War II. Knudsen was very active in war research. He helped to organize what became the Naval Undersea Research and Development Center in San Diego and served as its first research director. He also monitored NDRC contracts on research in artillery sound ranging in air.

In addition to the honors mentioned above, Knudsen received honorary degrees from Brigham Young University and UCLA. Thenew physics building erected at UCLA in 1964 was named in his honor.

BIBLIOGRAPHY

I. Original Works. A bibiography of Knudsen’s principal technical papers is included in Vern O. Knudsen: Collected Papers from the Journal of the Acoustical Society of America, 1. Rudnick and T. Bomba, comps. and eds. (New York, 1975). This volume contains the complete texts of Knudsen’s articles in Journal of the Acoustical Society of America.

II. Secondary Literature. Leo P. Delsasso: “The Gold Medal 1967. Vern Oliver Knudsen,” in Journal of the Acoustical Society of America. 42 (1967), 535–536; and Isadore Rudnick, “Vern Oliver Knudsen,” ibid., 56 (1974), 712–715.

Robert Lindsay