Acoustical Society of America
THE ACOUSTICAL SOCIETY honors itself in honoring Frederick Vinton Hunt as the 1969 recipient of its Gold Medal Award. Professor Hunt's career looms a varied and colorful as it has been successful. Teacher, administrator, inventor, and innovator—he has earned acclaim in many callings.
This is not the first time the Acoustical Society has honored Hunt. He has served on its Executive Council, has been its president and was a member of the Editorial Board of its JOURNAL. On 4 November 1965, the Society bestowed on him its medal honoring Pioneers of Underwater Acoustics "for his pioneering contributions to underwater acoustics as a scientist, innovator, teacher and administrator; and particularly for his unceasing efforts directed toward greater scientific understanding and more effective exploitation of sound in the sea."
In the fall of 1925, Ted Hunt enrolled at Harvard University after receiving two Bachelor's degrees—one in arts, one in electrical engineering—at Ohio State University. Three years later, with a Harvard Master's degree, he continued on his dual career by becoming Instructor in Physics and Communication Engineering (a joint appointment of the Faculty of Arts and Sciences and the Graduate School of Engineering). Almost immediately, he found himself in charge of laboratory instruction in acoustics in Cruft Laboratory. His stay at Harvard has been continuous since that time, and he has progressed through the ranks, not to one, but to two distinguished chairs—today he is both Rumford Professor of Physics and Gordon McKay Professor of Applied Physics.
Hunt's progress through graduate studies did not trace the shortest line. His propensity for diversionary interests and his nonconformity to academic rituals resulted in a double track toward the doctoral state. In fact, by 1934 he had submitted two doctoral theses, one to the Physics Department and the other to the Engineering School. Both these were accepted, and each of the departments placed his name on its tentative list of degree recipients. Seemingly, Hunt was headed toward being the first man at Harvard to earn the PhD and SD. But a timid Graduate School, wary of establishing a precedent, asked the new President, James Bryant Conant, to describe whether a man could earn two Harvard doctorates. President Conant ruled against the multiple award, and Hunt became instead the victim of the rule: one man, one degree. Because he had already completed the oral defense of his thesis in the Department of Physics, while his defense in Engineering was still scheduled for a day or two later, he chose to settle for the PhD in physics. Of course, both these, having been duly accepted, reside in Gordon McKay Library. He had already published his physics dissertation, on "Frequency Modulated Signals in Reverberation Measurements," in the Journal of the Acoustical Society a year before.
What was in that first paper of Hunt's? His object was twofold. First, he designed and built an accurate apparatus for detailing sound-decay curves as recorded in a room. Then, he set out to determine how a warble tone might be used to reduce the systematic deviations in the decay curves. He concluded that the deviations were highly repeatable but were critically dependent on the positions of the microphone and loudspeaker in the chamber and on the frequency of the source. He determined the optimum range for a warble frequency and he assigned limits of uncertainty to decay rates regardless of the type of source used. That paper glistens with Ted Hunt's attention to experimental detail and his persistence in penetrating to the meaning of his data. These are the qualities that for 35 years his tutelage has imprinted on his doctoral students.
In the summer of 1932 Hunt's roommate, Stephen Buckingham, asked him to squire his sister Katherine around Boston while she was in town to attend a wedding. Katherine has received her Bachelor of Science degree in Architecture at MIT and had returned to her home city of Washington, D.C. The friendly favor brought its own reward. Ted and Katherine were married the following November and took an apartment on Kirkland Street, a short walk from the Cruft and Jefferson Laboratories at Harvard. The Hunts have one son, Thomas, who works in low-temperature physics at the Ford Scientific Research Laboratory in Dearborn, Michigan.
In 1932, the exodus of the university community to the suburbs had not yet started, and many of the faculty at MIT and Harvard lived within walking distance of their work. So it was that the Hunts' neighbors turned out to include Philip M. Morse, then a quantum physicist at MIT, and W.L. Barrow, who was working in acoustics. With Barrow, who lived downstairs in the same building, Hunt carried on a continuing discussion of acoustics. Barrow, in turn, commuted to MIT with Morse, so there was plenty of opportunity for acoustical cross fertilization.
At Harvard, Hunt worked amid a spectacular array of physicists and engineers. There was George Washington Pierce, inventor of the rf crystal oscillator and of magnetostriction transducers for underwater sound; Edwin H. Hall of the Hall effect, the forerunner of modern solid-state physics; Theodore Lyman of the Lyman lines in optical spectroscopy; Percy W. Bridgman, Nobel Laureate, whose wife had been secretary to Wallace Sabine; A. E. Kennelly of the Heaviside—Kennelly layer; W. F. Osgood, the mathematician; O. D. Kellogg of potential theory; and F. A. Saunders who was technical heir at Harvard to Wallace Sabine. These men all attended the weekly physics and engineering seminars. Each was familiar with the others' research and publications. Hunt became known at these seminars for his superb demonstrations and his novel ideas.
But let us not lose track of that second doctoral thesis. It was titled "A Direct-Reading Frequency Meter," and its essence appeared in the Review of Scientific Instruments in early 1935. Shortly after its publication, an engineer at the General Radio Company called Hunt to say that G.R. was interested in the device and would like to study his notebooks. Soon thereafter, General Radio signed a royalty agreement and helped secure the first of Hunt's dozen or more patents. The instrument appeared on the market in late 1936. Its first significant application was in the analysis of telemetered signals from radiosonde balloons. During World War II, it was put to work measuring rf frequency deviation on nearly every ship of the fleet. The royalties therefrom provided a welcome increment to an academic standard of living.
Hunt has described this approach to electronic design as "functional." You start with the result you want, and then you try to devise a circuit that will achieve your goal. The frequency meter testifies to the validity of that approach to design.
By 1937, Assistant Professor Hunt was ensconced in a large corner room in Cruft Laboratory with hundreds of square feet of table and cabinet space. To the graduate students, those tables were known as "Hunt's junk heap." for they housed a bizarre collection of electronic components and electroacoustic equipment. His closest colleagues at Cruft, Roger Hickman and John A. Pierce, knew it for the treasure trove it was. That year the University provided Hunt with funds to hire a graduate assistant. A lucky boy from Iowa got the job, and went on to become Hunt's first PhD. Things were humming. First, there was the regulated power supply. Hickman and Hunt had been working for over a year on the theory of a dc feedback circuit. This led to the development of a regulated dc power supply that could control the voltage to a vacuum-tube amplifier to any desired precision. Described in the Review of Scientific Instruments in 1939, these power supplies were built in large numbers in laboratories throughout the country during the war years.
In September 1936, when Harvard University celebrated its tercentenary, Hunt and Jack Pierce undertook to record the words of that memorable occasion on acetate disk records. They decided that to play these disks back with the standard 5-oz phonograph pickups of that day would ruin them, and so they set out to build a lightweight pickup. Success was theirs. The cover of the March 1938 issue of Electronics carried a photograph of the first truly lightweight (5 g) pickup.
The phonograph-pickup adventure reverberated the halls of Harvard's Physic Laboratories. Hunt and Beranek designed and built a large, exponential folded-horn loudspeaker, a set of adjustable low-pass filters, and a high-power audio amplifier, probably one of the earliest with a large dose of negative feedback. Thus, Harvard became infected with its first high-fidelity fanatics. The singing strings in Brahm's First Symphony, the Scherzo from Beethoven's Seventh, and Strauss's "Also Sprach Zarathustra" became the test records, always played at 100-dB levels to simulate Symphony Hall's impact. Phonograph pickup after phonograph pickup flowed through Cruft's machine shops. Viscoloid damping, Hamilton's equations, stylus radii, normal modes of vibration, groove deformation, and background noise provided the daily thrills of a moon landing. Dr. Hunt never seemed to tire. His cheery acceptance of setbacks, his adoption of new tacks after skull sessions lasting to 3 AM, and his steady optimism made each day the exciting adventure that was to become a secret of his success with graduate students.
Neither the regulated power supply nor the lightweight pickup added to the flow of royalties, however. The power supply was not patented and, though several manufacturers expressed interest in the pickup, other inventions got around its patented features. But the endeavor led Hunt and Pierce and several graduate students to develop a workable theory of stylus—groove relations in phonograph disks. This research attracted international attention, and in 1954 the Audio Engineering Society presented their Berliner Award to Hunt for his work "particularly in the recording and reproductions of sound." In 1965, they honored him again with the Potts Memorial Award for "outstanding achievement in tracing distortion encountered in disc reproduction."
In the fall of 1936, Philip Morse published his book on Vibration and Sound,, of which Chapter VIII, "Standing Waves of Sound," was to stimulate research in acoustics for the next decade. Professor Hunt immediately incorporated Chapter VIII into his acoustics course and embarked, with his research assistant and a graduate student, Dah-You-Maa, on a research program that spawned a series of papers and two theses and delved into many facets of the "new room acoustics": steady-state transmission measurements, distribution of Eigentones, analysis of sound decay in rectangular rooms, and other topics.
A symposium chaired by Hunt at the Acoustical Society Meeting in New York in May 1939 brought into focus the work on the "new room acoustics" in papers presented by Hunt, P . M. Morse, N. B. Bhatt, R. H. Bolt, L. L. Beranek, and D. Y. Maa. The heady feel of a breakthrough was summed up in Hunt's closing statement that recent years had been "stirring times in the field of architectural acoustics."
The clouds of World War II had gathered, and in 1939 the storm had broken. In 1940, when the military undertook to organize so-called "defense research" on urgent acoustical problems, it was Ted Hunt who helped to launch the Harvard Psycho-Acoustic Laboratory under the direction of S. S. Stevens and the Electro-Acoustic Laboratory under the direction of L. L. Beranek; a mine countermeasure project at MIT under Cyril Harris; and an infrared project at Harvard under E. L. Chaffee.
In 1941, in response to the havoc caused by Germany submarines, Hunt, too, was drawn into what was now called "war research," as director of the Harvard Underwater Sound Laboratory. Hunt has since call that laboratory "a rollicking free-wheeling outfit of unique character. . . . NDRC . . .made it possible for us to stick our necks out, . . . we were undertaking tacks that couldn't be brought off unless somebody invented something between now and then, and, happily, somebody usually did. . . . My testimony is that we had an awful lot of fun working our heads off."
In four years, the accomplishments of the Underwater Sound Laboratory were immense. In sonar, they were responsible for the concept of simultaneous lobe comparison, which came to be known as the Bearing Deviation Indicator (BDI). Today's sonar systems are still based on the scanning sonar which proved its utility during World War II. The acoustic torpedo, developed simultaneously at both Hunt's laboratory and the Bell Telephone Laboratories, is credited with knocking out enough energy submarines to attenuate that major threat.
At the end of the war, the Harvard Underwater Sound Laboratory was disbanded. But its scanning-sonar effort was transferred to the U.S. Navy Underwater Sound Laboratory at New London; its torpedo project to Pennsylvania State University.
In June 1945, President Conant conferred on Frederick Vinton Hunt an honorary Doctor of Science degree with the words: "Originator and able chief of one of Harvard's large war laboratories, his ingenuity has served the Navy in its battles below the waves." Here, in embellished form, was the Doctor of Science degree that Harvard withheld in an earlier year.
Hunt speaks of three periods in his professional life: The first period, before 1941, when he did things himself; then the war years, in which he did things through a large research organization; and the years since the war, when he has stimulated his students to do things. To date, 34 students have received their doctoral degrees under his direction; another half-dozen left Harvard to complete their doctorates elsewhere; and four students now work toward a PhD under his direction. Of the 273 students who have taken his graduate course, 41 went on to the PhD, of whom 32 are now on the roster of the Acoustical Society. The thesis topics of Hunt's students sound like the table of contents of textbook on electroacoustics: room acoustics, audio communication systems, recording, physics of media, diffraction, acoustic arrays, sound in liquids, sound sources . . . Ten of his students earned PhD's before 1950; 14 in the nineteen fifties, and 10 so far in the sixties, a remarkably steady output.
Dr. Hunt has been a most valuable member of the Acoustical Society of America. Member of its Executive Council from 1938 to 1941 and President from 1951 to 1952, he has continued as an unofficial member of all of the Society's committees. Without guile or threat to his colleagues' pride, he serves as confidant to all.
His colorful papers have repeatedly sparked the Society's meetings. Typically, at Penn State he refused to use the light pointer and podium provided for the speaker; instead he seized a window pole and jumped on the lecture-room demonstration bench to breath life into his illustration. He stimulated the Society's satirist, Pat Norris, to continue his indomitable pricking of superficial research and related matters. In happy voice, he encourages the timid scientist in his first Society appearance before an audience jaded with parallel sessions.
What better way to close then to tell you about Hunt's plans for the future? He has in design a novel device for indicating when a moving acoustical source passes near a monitoring microphone. The principles were described at the Acoustical Society meeting in November 1965. He is currently taking experimental data to verify that the device is indeed a good system.
In two years, when Professor Hunt reaches retirement age at Harvard, he and his architect–wife plan to build their dream house on the bluffs of La Jolla, California, overlooking the Pacific Ocean. There Ted will tackle a whole row of writing projects, among them a long-pondered history of acoustics. He should be able to keep an ear open to underwater sound as well, both as a valued member of the NAS–NRC Committee on Underseas Warfare and as a near neighbor of the Scripps Institution of Oceanography.
Leo L. Beranek
Gold Medal Award - 1969Frederick Vinton Hunt