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essay This essay on the work of 19th-Century German physician, physicist and philosopher Hermann von Helmholtz is the culmination of a compressed yet nevertheless wide-ranging exploration of the man and his work which began as a search for understanding of Helmholtzian thermodynamics and evolved instead into an analysis of the scientist's work in acoustical research, and his early forays into the psychophysics of human perception. The intent of this essay is two-fold: to both trace the trajectory of Helmholtz's life and the scientific pursuits which lead him into early psychophysical sensory research, and to demonstrate an at least basic, passing knowledge of the physical theorems and processes that formed the basis of his work. It should be noted that, while Helmholtz did psychophysical experimentation in both vision and sound, the analysis here will be confined to an examination of the latter for reasons of clarity and space. Comprising the basis of this examination are the four texts of this month's reading, anchored by the hernia-inducing Hermann von Helmholtz and the Foundations of 19th-Century Science. A hefty 636-page anthology edited by David Cahan, Foundations provided the, yes, foundation as well as the scope and direction of this essay with a full-bodied critical overview of the entire spectrum of Helmholtz's scientific pursuits. It was upon these pages, in search of thermodynamics, that I discovered Helmholtz's musical interests and accomplishments. This revelation led me to the only English-language complete biography of Helmholtz readily available, a 1965 translation of Leo Koenigsberger's account originally published in Germany in 1902. The trail continued into John Backus' 1969 volume, The Acoustical Foundations of Music, and John Roederer's Introduction to the Physics and Psychophysics of Music. These books I found primarily helpful in that they disseminated deeply arcane information in largely layman-accessible terms. Other books I perused delved more deeply into the physics of sound and acoustics, but assumed a grasp of the language of physics -- namely, formulaic symbolism -- I simply do not have. The extend the musical connection, much of the physical examinations in other volumes I attempted was like being presented with a song in musical notation only and being told, "OK, whistle this." Cahan's Foundations provided me the basis of this essay on two levels. First is the quote that simply leaped out at me late one night after I had discarded thermodynamics for a musical bent, but remained uncertain as to where it was leading. "He (Helmholtz) pointedly characterized the relationship between the object and the sensations: 'the sensations of light...color (and sound) are only signs for relations in reality,' writes Stephen Vogel in his essay, "Sensations of Tone, Perception of Sound, and Empiricism: Helmholtz's Physiological Acoustics", quoting here from Ueber die Natur der menschlichen Sinnesempfindugen, Helmholtz's 1852 inquiry into the relationship between sensations and the object(s) perceived. "Just as there is no similarity between, say, the name of an individual and the actual individual, so there is no similarity between the sensations of an object and the object itself" (282). This rang an immediate philosophical bell with me, along the lines of constant imponderables such as, "do we exist in an actual reality or merely in our perception of it?" The second basis was found in Vogel's examination of Helmholtz's 1856 paper, Tonempfindugen, in which the scientist proposed his "tripartite division" of physiological acoustical perception. First was the physical part, "'which treats the conduction of the motions to which sound is due, from the entrance of the external ear to the expansion of the nerves in the labyrinth of the inner ear.'" Second was the physiological part, which dealt with "'the various modes in which the nerves themselves are excited, giving rise to their various sensations'", and third was the psychological part, which seeks "'the laws according to which these sensations result in mental images of determinate external objects, that is, in perceptions'" (285). Accordingly, this month's study evolved into the physical, the physiological and the psychological aspects of our perception of sound and of the images our perception of those sounds create. We will see how, while in fact there is no connection between a particular musical passage and the physical object of a Beethoven, a John Coltrane or a Radiohead, our perception of the stimuli objectifies our response. We will also see how Helmholtz trailblazed the scientific community's first understanding not only of the psychology of objectification, but also the physiology of acoustical processing. Unashamedly confessing to a profound preference of music over thermodynamics, this study again took a turn when I began to explore the breakdown of complex musical sounds into their basic components of tone and vibration. Having just recently completed the sound design for a short film, I had no idea of the level of complexity I was dealing with as I contemplated the graphic displays of various computer programs, a pair of headphones clamped on. As I began to discover how sound moves and is processed by the ear (an astoundingly complex and disconcertingly fragile procedure most of us take completely for granted), I found I shared Herr Helmholtz's fascination with the more amorphous process of objectification. Through all of this sound and science, is there any connection whatsoever to Anton Chekhov, ones which may be drawn without going to a contortionist's extremes? Happily, yes. Helmholtz and Chekhov were both physicians who moved on to other fields. Helmholtz's journey perhaps did not take him as far afield as Chekhov's medicine-to-literature, but Helmholtz's interests were undeniably widely varied and eclectic within the general scientific field, an expanse of interests ably noted in Foundations (and responsible in part for its massive girth). For me, however, the strongest link between Helmholtz and Chekhov is the most intangible. Perhaps meant to forever elude me because I did not make note of the source, when leafing through potential source material on Helmholtz at the local UC library, I came upon a recollection of a contemporary colleague, who recalled visiting Helmholtz at his residence one day to find him yelling into his piano as part of an experiment in acoustical reverberation. That struck me as a peculiarly Chekhovian vignette. Hermann von Helmholtz was by any standard a learned, accomplished and respected scientist who explored and excelled in numerous disciplines. To encapsulate the biography by the same name, Helmholtz was at various times in his long career Military Surgeon in the Prussian Army, Teacher of Anatomy at the Academy of Arts in Berlin, Professor of Pathology and Physiology at Königsberg, Professor of Anatomy at Bonn, Professor of Physiology in Heidelberg, and Professor of Physics at the University of Berlin, the latter post one he held for twenty years. Koenigsberger's biography of Helmholtz is in some ways a relief to read and others an annoyance. On the one hand, after plowing through even basic layman's physics, a familiar linear progression of chronological events was a welcome change. On the other, the apparent verbatim translation from the original 1902 text makes for an archaically colloquial and often tiring reading experience. What's worse, the book has no index whatsoever, and the table of contents is a dense, uneven running chronology of Helmholtz's life that randomly omits page numbers and key events. For example, in the preface to the English edition, the writer (someone identified only as "Kelvin", notes that "[h]is Tonempfindungen and Physiological Optics are not mere textbooks: they are ever-memorable Principia on the perception of sound...by living creatures" (iii). Indeed, Helmholtz's groundbreaking 1856 position paper on physiological acoustics proved to be a key component in this study, just as it was one I was not immediately struck by the significance of. Lectures, events and papers not immediately noted can be exasperatingly difficult to locate again in this text, especially when dealing with titles such as Königsberger natur wissenschaftliche Unterhaltungen and Ueber die Klangfarbe der Vocale. Despite these shortcomings, and considering the fact that this was the only biography on Helmholtz in English that I had ready access to, Helmholtz provides a seemingly thorough if unremarkable portrait of an extraordinary man. Born in Potsdam on 31 August 1821, Helmholtz was accepted two months past his 17th birthday into the Royal Friedrich Wilhelm Institute for Medicine and Surgery in Berlin, where he studied for four years. Upon his arrival he noted to his parents that "'I got here safely on Friday. My things arrived shortly after. The servant and the porter made difficulties at first on account of the piano, as there was no place for it in my quarters'" (13). Good help is hard to find. A first year medical student who brings a piano with his suitcase may have served to set Helmholtz apart from his classmates even before his intellectual prowess became known. It was here at the Institute that Helmholtz first encountered his lifelong mentor, Johannes Müller. Müller had "emancipated" himself from the favored metaphysical grounding of contemporary scientific thought, demanding "an empirical foundation for all scientific concepts" from his students (Helmholtz, 22). The effect upon Helmholtz was profound if not immediate, and laid the foundation for, among many other things, his theses in acoustical research. Before examining Helmholtz's empirical approach to acoustics, specifically the construct of the human ear and it's processing of sound, and how this lead him into an early exploration of psychophysics, it might be useful to explore some the very basis of this procedure, how sound is received by the ear and the physicalities of its process. Here I will attempt to provide not only a basic understanding but a further appreciation for what most of us take entirely for granted. For as John Backus notes early in his Acoustical Foundations of Music, "The science of physics begins by considering objects and concepts with which we are intuitively familiar because we deal with them constantly in our everyday experience. However, the discipline of physics refines our thinking about these things not only by defining them as rigorously as possible, but also by making these definitions quantitative" (3). This straightahead pocket summary, simply put, exemplifies Backus' entire book -- the occasional foray into arcane formulas aside. Both Acoustical and Roederer's Psychophysics give extensively detailed dissemination of the almost impossibly intricate physical chain of events involved in the movement of sound from the pinna or external portion of our ears, to the brain. The upshot of it all for me? Never shall I listen to loud music through headphones again. I would only see these incredibly fragile components violently vibrating. Rage Against The Machine may never sound the same. My preference and patience lay with the Backus book. Roederer is soon caught up -- and remains throughout his book -- with the graphical output of various formulas of sound transference. As Roederer notes near the beginning of his chapter, "Sound Vibrations, Pure Tones and the Perceptions of Pitch", his work is centered upon the delineation and graphical display of various (admittedly simple) physical experiments. "From the practical point of view," he disclaims, "...the experiments that we shall present and analyze...necessarily require electronic generation of sound rather than natural production with real musical instruments. Whenever possible, however, we shall indicate how a given experiment could be performed with real instruments" (12). In the reality of this reader's world, the practical point of view requires a prerequisite of Physics 101 to fully grasp the author's piggybacking formulaic profferings, their apologetic presentation notwithstanding. Fortunately, when Psychophysics begins to leave me in its chalkdust, Acoustical Foundations often steps in to help clear the air. A combination of the two texts provided me with the following rather fascinating process, boiled down here to the simplest disclosure of my understanding. Sound moves through the air in waves, causing vibrations which are channeled from the pinna (adjustable in such animals as cats and dogs to help funnel sounds, but basically useless appendages in "evolved" humans) along the auditory canal, a tube about three centimeters long which ends at the eardrum (Acoustical, 80). When the eardrum is buzzed, as it were, the mechanical vibrations are converted in the inner ear into nerve impulses that are "signaled to the brain and interpreted as sound" (Psychophysics, 17). This path involves transference through the middle ear, which is connected to the back of the throat by the Eustachian tube "so that changes in the ambient air pressure may be equalized and not cause large distortions of the eardrum" (Acoustical, 80). Now the journey gets really interesting. Beyond the Eustachian equalizer lies an interconnected trio commonly known as the hammer, anvil and stirrup bones. The hammer is connected to the eardrum membrane, passing along vibrations both good and bad to the anvil and stirrup, which each serve to further channel and conduct the sound to the entrance of the inner ear known as the oval window (Acoustical, 80; Psychophysics, 18). Beyond the oval window lies the cochlea, another bony structure distinctively shaped like a snail's shell. The interior of the cochlea is filled with an uncompressible fluid, perilymph, and divided along its circular center by a soft partition known as the basilar membrane. These two chambers are connected at the far end of the inner ear by a small opening in the basilar membrane known as the helicotrema (Acoustical, 80). Also at this far end are thousands upon thousands of microscopic hair cells, which not only convert the mechanical vibrations to nerve impulses for input to the brain, but also reconnect us to Herr Helmholtz. During the Christmas, 1849 holidays, Helmholtz completed the experiments for a position paper entitled, "On The Rate Of Transmission Of Excitation In Nerve", a study (with frogs) in both the response of these hair cells to sound vibrations, and within that, the response of certain hair cells to certain frequencies only. The basis of this experiment reflected the empirical training insisted upon by Helmholtz's mentor, Johannes Müller, and was not particularly enthusiastically received by his colleagues at the time. Indeed, as Helmholtz wryly noted to his friend Emil du Bois-Reymond, the mechanics of his experiments involved intrascientific cooperation and sacrifice and only "'after a severe struggle, I have converted a bold mathematician, who gets somewhat confused over non-mathematical logic...to the doctrine of the conservation of energy..." (Helmholtz, 64). Such cross-disciplinary camaraderie was looked upon with such collective disdain by Helmholtz's contemporaries that the scope of his experiments was viewed as somewhat radical and more than a little troubling. "The essential feature of Helmholtz's approach to the study of sensory processes was...his ability to integrate mathematical, theoretical and instrumentational elements into a complex yet unified structure" (Foundations, 260). Helmholtz himself recalled that during this time, a well-known physiologist recoiled in annoyance at the invitation of an equally well-known physicist to participate in one of the latter's experiments. 'A physiologist [has] nothing to do with experiments,' Helmholtz recalled the specialist sniffing, 'though they might be well enough for the physicists.' (Helmhholtz, 66). Nevertheless, Helmholtz plunged onward into the field of acoustical research, and by October, 1855, had begun to blend his interest and knowledge of music into his work on the human ear, folding into his detailed anatomical studies "research that was closely related to that on combination tones" (Foundations, 267). Helmholtz's plans were nothing if not ambitiously scaled upon this nebulous field. In January, 1857, he wrote to his colleague William Thomson:
With this brief and confident introduction, Helmholtz launched himself down the track that would expand upon his definitive Tonempfindungen and lead him beyond pure science into aesthetics and, ultimately, to the psychophysics of perception. The second part of Tonempfindungen involved an empirical analysis of harmonic relations with consonance and dissonance at the core. Gary Hatfield, in his analysis of the post-purely scientific Helmholtz, "Helmholtz and Classicism: The Science of Aesthetics and the Aesthetics of Science" points out that "Helmholtz's confidence that partial tones exist and are uncovered through the analytical solvent of attention rested upon his conception of the relation between neural activity and sensation" (Foundations, 530). This is a key distinction and a key course of pursuit by Helmholtz, for it helped birth psychophysics as an aesthetic science. Here Helmholtz diverged from the more or less tangible study of the effect of sound waves upon the human receptor and began to forage about in the amorphous field of aesthetic perception, of inquiries into just what is it physically that makes a musical passage appealing. Helmholtz's initial posit that the appeal of structured musical sounds upon the human psyche "depend upon the orderly relations of the parts to the whole -- an orderly relation that is not so simple and obvious as to be readily made the object of conscious reflection but one which must be intuitively grasped (Foundations, 533) reminded me of what I once heard about what comprises a good pop song: the mixture of the familiar with the unexpected. It was this intangible process of perception that increasingly fascinated the mature Helmholtz and occupied a considerable portion of his professional life (the acoustical experiments begun in January, 1857, for example, would take more than eight years to complete). Ultimately, Helmholtz was driven to conclude that the aesthetic effect of musical sounds depended upon "an unconscious sensing of resemblance" between the tones themselves, which Hatfield compares to "that which allows us to detect the resemblance between the faces of members of a family" we may not know (Foundations, 534). The philosophical can of worms Helmholtz opened with this avenue of concentrated pursuit continued well after his death in 1894 and on into our present times. Indeed, John Roederer expands upon Helmholtz's theories in his Introduction to the Physics and Psychophysics of Music, proposing that musical appreciation is more of a conditioned than a "natural" response. "Why don't we make music with continuously changing pitches that sound like...the 'songs' of whales and dolphins?" he wonders. His answer? "There is no simple answer to this question" (Psychophysics, 146). Roederer's theory, however, is typically complex and rooted in what he terms "closed-loop engrams" which, in a drastically reductive summary, puts forth that human inner ear hair cells act as a kind of reverberating short-term memory storage system, allowing received impulses to interact superimpositionally with newer, incoming stimuli (hence the closed-loop system) in what are commonly known as musical scales. "We believe," Roederer concludes, "that there are scales because it is easier for the brain to process, identify and store in its memory a melody that is made up of a time sequence of discrete pitch values that bear a certain relationship to each other rather than one that sweeps continuously up and down over all possible frequencies" (e.g., the aforementioned "whale songs") (Psychophysics, 146). Such a theory brings this overview, with gentle irony, full circle at last by offering a physiological explanation of the elusive nature of the psychophysical perception of music that Helmholtz himself most likely would have appreciated. Works Cited Backus, John. The Acoustical Foundations Of Music. New York: W.W. Norton & Co., 1969. Cahan, David, ed. Hermann Von Helmholtz And The Foundations Of 19th-Century Science. Berkeley: University of California Press, 1993. Koenigsberger, Leo. Hermann Von Helmholtz. New York: Dover Publications, 1965. Roederer, John G. Introduction To The Physics And Psychophysics Of Music. London: The English Universities Press, Ltd., 1973. Copyright © 2001 The Write Word, Inc. All rights reserved. |