Acoustical Society of America
Wallace Clement Sabine Award - 1974

Lothar Cremer

IF HE HAD DONE NOTHING in his professional life but discover the application of the "coincidence effect" to structures and then help us all to understand it, Lothar Cremer would richly deserve the award with which we honor him tonight. The ripples from that discovery have spread to every area of physics where vibration plays a part, though, of course, the practical impact is best known in building acoustics. But, his talents and energy have embraced a far wider span of interests.

In building acoustics his attention has ranged from structure-borne sound, including impact noise isolation, to sound attenuation in ducts, to transmission loss of single and double walls and cylindrical shells, to the theory of floating floors, and the effects of sound bridges in building structures. In concert hall acoustics, he has been responsible for the design of a number of well-known European halls, including the Berlin Philharmonie, the Opera House in Munich, and the Liederhalle in Stuttgart; he has also contributed to the design of a number of halls in the United States. As for musical acoustics, he has studied the behavior of organ pipes and violins. He has contributed to the theory of electromechanical transducers, and in the field of psychological acoustics he explained the "law of the first wavefront," the precedence effect. Above all, however, we must be grateful for his gifts as a teacher and for the great enthusiasm and precision he brings to his teaching and writing.

Lothar Cremer was born in Munich on 16 August 1905, and thus is Bavarian by birth. But he is equally a Berliner, for the family moved to Berlin when he was but six years old. He graduated from the gymnasium in Berlin in 1923 and began his higher education with practical studies with the Allgemeine Elektrizitäts Gesellschaft, a major electrical appliance industry. He subsequently moved on to the Technical University of Berlin-Charlottenburg, where he studied first mechanical, then electrical, engineering. During his student days at the University, he gained his first teaching experience as Assistant in the Institute of Technical Mechanics.

His doctoral thesis topic, still a matter of lively interest in the design of open plan offices today, was a theoretical and experimental investigation of the dependence of the sound absorption of porous surfaces upon the angle of incidence. Following the conferral of his doctorate in electro-acoustics in 1932, he became involved in the development of the German sound motion picture industry.

By 1933 he was working the acoustics division of the Heinrich Hertz Institute in Berlin(of which he later became the Director, in 1960); and, in 1934, he began his long professional association with the Technical University of Berlin, first as Assistant Professor and then, in 1940, as Docent in the Institute for Mechanical Engineering.

The early war years led Cremer back to Bavaria, near his birthplace, where he worked in underwater acoustics for the German Navy. He lived during this period in a small farm village between Munich and Augsburg.

After the war, he had the good luck to find on VE Day, 1945, that his family's multistory building in Munich was the only one left standing for blocks around in a sea of rubble. It was miraculous! This good fortune enabled him to return to normal life quickly and in 1946 to open his own acoustical consulting office in Munich, later with Helmut A. Müller as his assistant.

In 1949 he became a Reader at the University of Munich and in 1951 an "ausserplanmässiger Professor" (equivalent to Adjunct Professor in the U.S.). During these years his interest was drawn to the fields of room acoustics and noise control in buildings, and at this time he published the first part of his major technical literary work, The Scientific Fundamentals of Room Acoustics. The three volumes of this monumental work appeared in the years between 1949 and 1961; the final volume (Vol.2!) contains a wealth of practical solutions for architects and acoustical engineers.

In 1954 Cremer was called back as a full professor to the Technical University of Berlin, and was also made Director of the Institute for Technical Acoustics of the University. This Institute had to be built up almost from scratch, a feat which he accomplished with great success; the ITA is today one of the best known and most completely equipped acoustical institutions in the world. A year later, he was in addition named Director of the Acoustics Division of the Heinrich-Hertz Institute.

In the spring of 1954, just before moving from Munich back to Berlin, Cremer spent a six-month study period in the United States with BBN in Cambridge, an opportunity that laid the foundations for long and close relationships with his American acoustical colleagues. Since his return to Berlin, he has been increasingly "international" in his activities, being very active in ISO work, and contributing to the design of important concert halls in a number of countries. In addition, he has written two more major technical books, Körperschall ("Structure-borne Sound") in 1967 (with Manfred Heckl, recently translated into English by Eric Ungar) and Vorlesungen über technische Akustik ("Lectures on Technical Acoustics") in 1971.

In 1956 he was made a Fellow of the Acoustical Society of America, an honor that brought him great pleasure. His certificate of Fellowship in the Society has hung for years on the wall of his office, behind his desk.

Lothar Cremer is the ideal scientist/engineer: unremitting in his search for truth in the laboratory but also insistent that his solutions meet the practical needs of building design and construction. He is strict with his doctoral candidates, but relaxed and humorous with his graduates and colleagues.

His dominant professional characteristic is clarity; his writing and his lectures are exceptionally understandable. This does not necessarily mean that his lectures are easy to follow; as a matter of fact, because he presents an enormous amount of information in a lecture and almost never repeats himself, his lectures are quite demanding. I remember hearing one of this lectures at the University; it was so perfectly organized that it finished precisely at the end of the period, and every portion of the blackboard was covered with helpful summary statements and formulas. There was absolutely no space left over, but he had not had to erase anything to make more room.

Lothar Cremer may appear to some Americans who know him only professionally, as a "typical German professor": thorough, uncompromising, always completely immersed in what he is doing at each moment. To some extent this is true: Manfred Heckl remembers his own first seminar talk, after which Cremer advised him, "You talked as if, mentally, you had your hands in your pockets!* This is absolutely wrong: you must convey the impression that what you have to say is, at this moment, the most important thing in the world!" There is no doubt whatever that Cremer himself is both dedicated and devoted to his work at all times.

On the other hand, when work is over, no one is more ready for relaxation and conviviality. If he inherits his "Herr Professor" quality from his Rhinelander father (who was also a professor, as are his brother and sister), he derives his "Frohnatur" from his Bavarian mother: the happy, fun-loving temperament of the wine-drinking, music-making people of Bavaria. Fasching(Mardi Gras) festivities at his Institute were always happy and noisy, but never coarse. Cremer told many stories and jokes in different dialects, and was extremely charming to the ladies. There is room for fun even in his professional consulting activities. During his collaboration with architect Scharoun on the Berlin Philharmonie, the positions of the acoustic reflectors were usually represented with beer bottles and cigar boxes; and for weeks the conductor in the scale model of the hall was an empty beer bottle.

A fine example in which the "Herr Professor" and the "Frohnatur" are combined, also demonstrates the linguistic skill at Cremer's disposal: this is the ABC of Building Acoustics, a little primer in which Cremer's short, witty verses and a short semitechnical exposition were illustrated with amusing sketches drawn by Cremer's assistant, Dipl.-Ing. Joachim Nutsch.

When Cremer came for a six-month visit to BBN in 1954, BBN had been involved in applying the newly developed honeycomb materials for building a cheap, strong, lightweight audiometric booth; it was supposed to "beat the mass law" and to produce high transmission loss, portability, and all kinds of wonderful advantages on account of the high stiffness. Instead, it was a distinct flop, being pretty much sound transparent. When Cremer showed up, he surveyed the situation and then, as Herr Professor, waggled his finger and scolded, "Tsk, Tsk, you don't read my papers!"

Those who have worked with Cremer are familiar with his practical phrase: "I have a proposal"(Ich habe da einen Vorschlag"). He might use it, for example, to break out of a deadlock in technical discussion over an ISO test standard, or in a difficult consulting problem. I recall that during the remodeling of Orchestra Hall, Leo Beranek, Bill Watters, and I were discussing with Lothar how to resolve a certain question. Each of us had a different idea, each had a good argument in support of his suggestion, and none of us was about to give in. Lothar "had a proposal": he wrote each of the four ideas on a separate slip of paper and these slips were passed around; each of us wrote a number from 1 to 4 on the back of each slip to indicate his order of preference for the four solutions; the slip with the lowest total held the solution we adopted.

There is one of Cremer's scientific discoveries that even he may not be aware of: that is, a new unit of time, the "Crem," equal to about 17 minutes. Students at his Institute would come to his office to ask the secretary if they could speak with the Professor ( who was plainly visible through the open door, not doing much); they would be told to go back to their labs and the professor would see them shortly. It was usually one Crem later that Lothar would appear to discuss their problems.

It may also be true that his best performances outnumber his memories of them. Several years ago Cremer and some of his assistants went to Greece to make acoustical measurements in the old amphitheaters. Since Cremer was not very familiar with the equipment, his job was to carry the microphone from place to place. It was very hot that day, the steps were steep, and before long he was tired. The remarks he made to himself, as he carried the heavy cables up and down, are not for print; but, since they were made in front of the microphone, they were duly recorded on the tape. History does not record whether or not he ever heard a playback of this performance.

Ed Kerwin recalls that Lothar loves to sing and always joined happily in the BBN songfests. On one occasion, when they were returning together from New Hampshire and stopped for a picnic under the pines, Lothar was so moved by the beauty of the spot that he produced his viola and played during the lunch.

He also became quite fond of some of our American songs. Once, when he heard "America the Beautiful" sung at a picnic, he asked someone to write out the words on the back of a paper picnic plate(the only handy writing material at the moment); this he carefully put away and kept. (He was dismayed, however, at being served American beer from a can!)

As for practical jokes, Phyllis Beranek will probably never forget the occasion during a Fasching parade when Lothar arranged for a ferocious grizzly bear to leave the parade, climb up into the viewer's stands and give her a terrifying bear hug!

We have tried to suggest with these remarks tonight why Lothar is equally respected for his professional career and loved for his warm and friendly manner.

With his recent retirement from his responsibilities at the University of Berlin, we can, of course, expect no diminution of his technical activities, but only a change in emphasis and direction permitted by relief from administrative chores: he can now pursue those problems of special interest to himself for which the Director never had enough time. We wish him many more happy and productive years.

*A polite German always has a handkerchief in his pocket, but not his hands...certainly not while giving a speech!

Theodore J. Schultz