Eric Zepler’s new career in the Institute of Sound and Vibration Research from 1963 to 1973.
Words from Professor Chris Rice, formerly Director of ISVR and Dean of Engineering and Applied Science
During 1962 Professor E J Richards, the then Head of the Department of Aeronautics, was finalising arrangements for the establishment of the now internationally renowned Institute of Sound and Vibration Research (ISVR). With his retirement from the Department of Electronics pending, Eric Zepler was approached by Professor Richards to consider joining this new Institute as a Research Fellow to ‘provide essential mechanical and electronic backup to a group studying human responses to noise and vibration, including amongst other factors those induced by impulsive noise’.
Although this subject was not within his recognised fields of research interest he was nevertheless intrigued by the challenge and with the additional encouragement of Professor POAL Davies joined as one of the first newly appointed members of staff in October 1963. Working on a morning only basis he started out on a most successful new career, in what can only be described as modest accommodation for such an esteemed professor. He was sharing a room in the basement of the Tizard Building with a lecturer and a research student when I joined this small team as a Research Fellow in January 1964. Together we started on a ten year working collaboration which resulted, as those who have ever been closely associated with him will testify, in not only a stimulating research experience but also a personal friendship to be treasured.
As the research in audiology and subjective acoustics expanded the group was relocated in houses in University Road whilst three floors and custom build acoustic laboratories were added to the Tizard Building. It was in these environments that Eric Zepler developed his original research contributions and supervised many PhD students. A laboratory in the Rayleigh Building was subsequently named after him.
In the following pages I have written about his work on Sonic Boom Research and on Community Noise and Vibration Research, and also about “Zepler the Person”. Also I have included some memories of him as a research supervisor, written by Professors Roger Thornton and Michael Griffin.
The advent and subsequent development of Concorde required answers to questions relating to the human responses of communities exposed to the sonic booms of aircraft flying at supersonic speeds.
The study of such subjective reactions under laboratory conditions required facilities able to reproduce the classical N-pressure wave of the sonic boom to subjects listening not only through headphones but also under the more realistic circumstances of whole body exposure within an enclosed pressure booth. The electro-mechanical reproduction of N-waveforms having rise-times and decay durations of 1-10ms and 50-100ms respectively was no mean feat. Eric Zepler successfully applied his electronic skills to the successful development of both of these facilities which enabled many students to complete their higher degrees.
The headphone research enabled the formulation of theoretical models for the calculation of the loudness level of sonic booms from their pressure-time functions. The pressure booth allowed the simulation of a sonic boom under free-field conditions. The underlying principle was that loudspeakers built into the wall of the pressure-tight booth acted as pistons so allowing the faithful reproduction of N-waves. This was not an easy task as the mechanical impedance of a loudspeaker causes the waveform displacement to be different from the applied force, and Eric Zepler used electro-mechanical analogies to model the required responses of the loudspeaker coil so ensuring the correct outputs.
Eric Zepler also personally experienced the effects of the sonic boom at first hand when being overflown by military fighter aircraft during an ISVR team visit to Meppen in West Germany in 1969 to measure the acoustic and structurally induced vibration effects. He was invaluable on that occasion because he was able to interview members of the local population in order to obtain their subjective reactions at first hand.
The innovative Zepler concept of spectral weighted energy density developed during the sonic boom research was later extended to include other short duration and transient community sounds and led to the development of a loudness level meter for the quantitative measurement of impulsive sounds. A wide variety of such short duration sounds was studied including the loudness, pitch, and pre/post-stimulatory effects of masking of pure tones, complex waveforms, noise bursts and pistol shots. Such researches made valuable contributions to the debates which were taking place over the acceptability, measurement and control of community noise nuisance.
His skills were also extended into the area of whole-body vibration and human vision where, although not fully conversant with the finer details of the subject, his penetrating and inquiring mind and inspirational and innovative grasp of the basic issues involved provided invaluable support and inspiration to his students.
Those seeking a single source reference to his numerous research and other contributions to ISVR are referred to E E Zepler et al, Journal of Sound and Vibration (1973) 28(3), 375-401; Human Response to Transportation Noise and Vibration.
For readers who may not be familiar with the ethos of the ISVR it may be compared to a closely knit community that is so immensely proud of its self achieved success that it will fight tenaciously to retain it’s freedom and independence.
This inbred competitive nature has resulted in academic staff being very successful at gaining external financial support over the whole range of sound and vibration topics ranging from signal processing to medico-legal. These topic-centred wide ranging interests have generated a very confident and friendly atmosphere within which to work, and it was interesting to note how easily Eric Zepler fitted into this ethos which appears to have been present in the ISVR from the moment of its inception.
He was very personable with an endearingly dry sense of humour. I recall an incident that amused him greatly in the days when one car key fitted all. Having driven his green Triumph Herald car home for lunch he remarked to Laura his wife that he must get it looked at by the garage as it felt strange. She investigated the situation and was quick to point out that it was not his car and that he had better return it immediately to the University and come home with the right one. To play bridge with him was a cherished experience.
Although he was a hard taskmaster he tempered justice with mercy, as is reflected in the comments of one of his successful PhD students who wrote, after Sophocles, ‘This is the end of tears: No more lament’. The comments of others of his past students give testimony to his warmth as a person and to the value which was placed on his judgement. It is fitting to quote two examples by Professors Roger Thornton and M J Griffin.
In the spring of 1962 I arrived for the first time in Southampton, to be interviewed by Professor Zepler for a place on the BSc Electronics course that he had set up four years earlier. At that time only Southampton and Bangor had full undergraduate courses as opposed to others which offered third year options in Electrical Engineering. I was awarded a place and graduated in 1965.
In the meantime Eric Zepler had retired and started as a Research Fellow in ISVR. Naturally he looked to his old department for PhD students. Initially we worked on the sonic boom and our offices were in semi-detached houses in University Road. He was man with a large intellect and a real twinkle in his eye, who on arrival in this country had evidently read and completely digested Fowler’s ‘Modern English Usage’. Whilst he had a slight accent, his knowledge of grammar was amazing and I can still hear his voice saying, when reviewing the draft of a paper I had written, ‘Roger, you have a hanging participle.’
He could say a lot with very few words. One day he came into my rather untidy office and silently walked round observing the piles of paper, experimental worksheets and general detritus. When he got back to the door he said ‘Output is proportional to facility’ and left. He was an excellent supervisor who had the knack of drawing things from you that you didn’t know you possessed. Above all he was a kindly man and I, like many others, am better for having known him.
Roger Thornton, Professor of Hearing Sciences
An inspired teacher of how to think logically and express thoughts simply in the English Language.
A twinkle in the eye that engaged, intrigued and conveyed an inner understanding and strength.
He was always kind, patient and had both character and charm, especially with the ladies.
Was able to judge character from handwriting and not be too proud to rely on his predictions.
To observe him playing chess was to watch ‘grand master ballet’ with his moving hand – it was beautiful even without appreciating the significance of the moves.
Shortly before he retired he said that being a University Academic is one of the greatest privileges, and the opportunity should be treasured.
I think of Zepler not as a building but as a rock whose presence will last forever.
Michael Griffin, Professor of Human Factors