Purkyně’s Opistophone: the hearing ‘Deaf’, auditory attention and organic subjectivity in Prague psychophysical experiments, ca 1850s

ABSTRACT

The paper examines the little-known experiments in audition performed by the prominent experimental physiologist Jan Purkyně in Prague in the 1850s. Purkyně’s original research on spatial hearing and auditory attention is studied against the backdrop of the nineteenth century research on binaural audition and the nascent field of psychophysics. The article revolves around an acoustic research instrument of Purkyně’s own making, the opistophone, in which hearing became both an object of investigation and an instrument of scientific inquiry. It argues that Purkyně’s understanding of auditory attention, which combined acoustic stimulation, physiological conditions, and sensory training, preceded a similar approach to hearing in psychophysical debates in the second half of the nineteenth century. Purkyně was the first scholar to experimentally investigate intracranial sounds, which he studied in his experiments with the inmates of the Prague Institute of Deaf-Mutes. This research on intracranial hearing was part of Purkyně’s study of so-called organic subjectivity, in which subjective hearing experience was interpreted as the result of the interaction between individual perception and objective acoustic phenomena.

KEYWORDS:

• Psychophysics
• psychoacoustics
• binaural hearing
• auditory attention
• sound experiment
• Jan Purkyně
• experimental physiology
• organic subjectivity

1. Introduction

In November 1859, Jan Evangalista Purkyně (1787-1869), a Czech scientific superstar and one of the founders of experimental physiology, received a letter from a certain J. Fr. Halem, a resident of the German region of Herzogthum Holstein, inquiring about an apparatus professor Purkyně had reportedly invented during his experiments at the Prague Institute for Deaf-Mutes,¹ which enabled the deaf to hear again. Herr Halem wanted to purchase the hearing aid immediately and was keen on finding out more about its size and effectiveness and the way it was constructed, calling Jan Purkyně a ‘blessing for the deaf’ (ein Segen für Taube) if it turned out that the information was correct.² Similar letters followed shortly afterwards: in February 1860, a deaf apothecary from Russian Tanganrog expressed his enthusiasm at learning from the local newspaper that Purkyně’s apparatus restored hearing in those who were born completely deaf (völlig taube) and was interested in either ordering the instrument or obtaining detailed instructions for its construction.³ The news that a Czech professor in Prague had invented a remarkable hearing apparatus spread all over Europe and newspapers were quick to reprint the information that out of thirteen deaf people, eleven had started to hear again when assisted with Purkyně’s hearing aid.⁴ But what was it, exactly, that Purkyně invented, and what does it tell us about sound-based research in Prague at the time?

From Purkyně’s correspondence, academic lectures, and scientific articles from around the 1850s, there emerges a curious scientific instrument, the opistophone.⁵ The instrument, which is also referred to as Doppelhörrohrs (double hearing tubes) or, in one of its versions, the Ear of Dionysus, was employed in numerous experiments in which Purkyně observed how different material conditions impacted the way both one and two ears perceived sound. In what follows, I will examine Purkyně’s experiments in audition against the backdrop of nineteenth century research on spatial hearing and binaural audition, discuss his project of experimental physiology in the context of the nascent field of psychophysics, and introduce Purkyně’s concept of organic subjectivity, as it contributed to the formulation of ideas about the nature of objective knowledge and its relationship to subjective perceptual experience.

2. Purkyně’s experimental physiology and the ‘sonic turn’

A number of disciplines started to investigate phenomena such as speech sounds, spatial hearing, the human voice, auditory attention, noise, auditory memory, and musical listening in the long nineteenth century.⁶ Historians of science sometimes talk about a ‘sonic turn’, which was marked by the emergence of a growing number of disciplines concerned with the phenomenon of sound in France and the German-speaking world in the second half of the 19th and early twentieth century.⁷ Sound-based research in Prague played its role in these histories – it was there that Ernst Mach performed some of his psychophysical experiments from the 1870s to 1890s, in which hearing became both an instrument and an object of scientific knowledge.⁸ The history of sonic investigations in Bohemia, which became increasingly tied up with Czech-speaking Academia and the national culture in the course of the century, however, remains yet to be written. Purkyně’s original experiments in human audition from the 1850s, which are largely missing from historiographical accounts,⁹ indicate that sound-based research in Bohemia and the nature of its relationship to the study of sound and hearing in the German-speaking word, France, and Great Britain merits further investigation. By looking closely at the history of the opistophone, the paper will show that Purkyně’s investigations of the parameters of spatial hearing and subjective auditory experience prefigured – both experimentally and theoretically – much of the work published on the subject in the later decades of the century.

Purkyně’s research on hearing was part of his project of experimental physiology. Although he took interest in acoustics and the spatial figurations of sound early in his career, human audition was a subject he systematically investigated later in his life. Similarly to other prominent scientific figures of the time, his investigations included a remarkable range and scope of subjects. He made basic contributions to numerous fields and disciplines, and opened new avenues of research in histology, embryology, dactyloscopy, and cellular biology. He studied phenomena such as vertigo, double-vision, afterimages (Nachbilder), and photomicrography, and made many discoveries, some of which were rediscovered later by other scholars.¹⁰ His research on hearing, formed at the crossroads of physiology, psychology, acoustics, deaf pedagogy, but also natural philosophy, was no exception.

Jan Purkyně received his degree in medicine from Charles University in Prague in 1818,¹¹ after which he took up the job of Assistant in anatomy and physiology. In 1823, he accepted the position of the chair of Physiology at the University of Breslau in Prussia (the German part of Silesia, today’s Wroclaw, Poland), where he remained for most of his career, from 1823 to 1850. His Czech origin seems to have been a considerable obstacle, not only on his way to the professorship in Prussia – which he was offered partly thanks to the influence of prominent personae such as Johann Wolfgang Goethe and the Berlin professor of anatomy Karl Asmund Rudolphi – but also on his way up through the German-speaking academic structures.¹² Nevertheless, Purkyně’s stay in Breslau turned out to be a success. Apart from his prolific scientific work, his single most important achievement was arguably the foundation of the first modern Physiological Institute in 1839, which inaugurated a new tradition in the study of physiology, one based on rigorous experiment.¹³

In Purkyně’s view, the modern physician should educate himself not only in books and in the clinic, but also in physiology grounded in experimental laboratory investigation. He set up the first physiological laboratory in his own workplace at the university, yet, because his pedagogical methods caused constant friction with his colleagues, he ultimately moved the lab to his own apartment, where he met with students, performed experiments, constructed scientific instruments, and also ate and slept. The painstaking process of establishing the Institute in Breslau is not the subject of this paper; however, the experimental methods in teaching and research that Purkyně developed there are instrumental for understanding his research on sensory perception. To find out about specific characteristics of the senses, Purkyně designed and carried out a great number of self-experiments, in which he irritated his eyeballs, swallowed digitalis, licked sugar patterns on glass plates, stuck glass tubes into his nostrils, exposed his back to streams of hot and cold water, and, pertinently to this paper, examined auditory perception under different material conditions.¹⁴ Self-experiment, which fell under the rubric of what Purkyně described as heautognosis (the Greek term for self-knowledge) was a standard part of his scientific practice, in which he set out to discover and theoretically explain the objective grounds of subjective experience. The principle of heautognosis received criticism from some of his contemporaries, including the physiologist Johannes Müller and Johann Wolfgang Goethe,¹⁵ but Purkyně’s painstaking and systematic self-observation was nonetheless able to produce generally recognized knowledge and, as shown in this paper, helped him formulate research questions to be further investigated under different experimental conditions.

Although the idea of sound as a vibration goes back to Antiquity, and Aristotle’s metaphor of sound waves as ripples on the surface of water continued to define the notion of how sound travelled till modernity,¹⁶ it was not until the 19th and early 20^th centuries that sound came to be fully understood as a spatial phenomenon. The relationship between hearing and the perception of space long remained unclear, and the capacity of the ear to yield valid information about the acoustic environment was called into question even in the beginning of the twentieth century.¹⁷ This imperfect understanding of the spatial characteristics of human hearing was epitomized in the discussion of binaural audition; that is, knowledge of the physiological mechanism of listening by both ears was very limited up until the second half of the nineteenth century and the notion of ‘auditory space’ was not modelled solely on hearing capacities either.

An important step in the modern articulation of the exact relationship between sound and space were attempts at sound visualization. Spatial figurations of sound were famously introduced by Ernst Chladni in the late 1880s. His experiments with a thin layer of sand on glass or metal plates of different shapes demonstrated that different acoustic frequencies formed specific figures (Klangfiguren) on the surface and showed that sound itself could produce an objective visual record, this a direct reflection of its physical properties. Inspired by Lichtenberg’s visualizations of electric polarity (1777), Chladni’s experiments were highly popular at the time and sparked the imagination of many authors, including J. W. Goethe and Jan Purkyně.¹⁸ Purkyně took interest in Chladni’s experiments early in his career and effectively refined his work by using liquid instead of sand in the demonstrations. A small wooden box containing Purkyně’s glass plates with sound figures was discovered in Goethe’s collection in Weimar, together with the letters the two scholars had exchanged about the subject.¹⁹ Goethe was intrigued by Purkyně’s work on the senses, especially on subjective vision, and both authors shared an interest in the objective principles of translating sound into visual form.²⁰ Drawing on his acoustic experiments, Purkyně concluded that aural and visual events had the same objective foundations, these understandable in terms of phenomena such as vibration and oscillation. The notions of sound and acoustic vibrations as universal elements that synthetized sensible knowledge connected Purkyně’s thought to the German romanticist Naturphilosophie.²¹

In his physiology project, Purkyně preferred experiment to speculation. It is for this reason that the tradition of experimental physiology he founded in Breslau is sometimes quoted as a prime example of modern objective science. However, in the study of Purkyně’s work on the senses, it is important to keep in mind not only that it found itself at the intersection of fields of inquiry such as anatomy, physics, and experimental psychology, but that it had also a strong metaphysical and natural-philosophical underpinning. It was against the backdrop of his idea of the evolution of the Earth Spirit (Erdgeist) through human spiritual and scientific progress that his work on sensory perception developed. In his metaphysical writings, the Earth was understood as a living animate organism, with natural forces as its sensory organs; Purkyně’s finding that the whole body participated in sense perception (and thus indirectly also in thinking) by means of neural pathways and their peripheral endings was applied analogously to the large organism of the Earth.²² The experiments in audition, too, were performed against such a philosophical background. Although the idea of acoustic vibrations as a unifying natural principle did not directly influence the character of the experimental research into hearing Purkyně conducted during his Prague period, his life-long interest in the relationship between subjective and objective knowledge, as well as the principle of heautognosis, grew out of his natural-philosophical thought.

It was not until 1850, when he was 63 years old, that Purkyně was able to return to Prague as a professor of Physiology. Apart from his academic work, he took an active part in cultural, educational, and political life in Bohemia, where he became a member of different scientific as well as cultural societies and regularly contributed to Czech-language journals such as Journal for the Bohemian National Museum, and, most importantly, Journal of Natural History, Živa, of which he was a founder and editor. Although historiography has long suggested that Purkyně did not carry out any original scientific research after his return to Prague,²³ in the remaining part of this paper, I will show that, as regards his experiments in audition, this was not the case.

3. Opistophone: the first round of experiments

The exact design of the hearing instrument requested from Purkyně by newspaper readers in the late 1850s is unknown and, to my knowledge, none of its drawings have been preserved. The alleged hearing aid, which goes by different names in historical documents, seems in fact to have encompassed several instruments of slightly different design, which, however, operated on the same principle.

In his letter, J. F. Halem described a hearing aid he purchased in Hamburg a few years before: it was a 2 ½ cubit²⁴ long tube made of Gutta Percha with a pointed (hörnerne) end that was to be inserted in the ear, and a funnel for speaking on the other end of the tube. Not only did it improve Herr. Halem’s ability to hear words (if uttered directly into the funnel), but it was also easily transportable, as the flexible rubber tube could be rolled up and carried in a bag. He hoped that Purkyně had invented something more sophisticated and effective: a hearing aid that would enable its user to fully understand the conversation in a room and take an active part in it.

The information that out of thirteen deaf subjects, eleven started to hear when listening through Purkyně’s opistophone appeared remarkable. Although Purkyně had to discourage enthusiasm about the invention of a miraculous hearing aid and point out that the apparatus had so far only a theoretical value, he continued working on the topic and envisioned various applications of the apparatus. As the first versions of the instrument suggest, however, his long-term goals were mostly theoretical.²⁵

Purkyně’s basic design of the opistophone resembled the stethophone (or differential stethoscope as it was also called) of Somerville Scott Alison, which was first introduced in England in 1859.²⁶ Alison had modified the design of the binaural stethoscope invented in the early 1850s, which transported sound from one source simultaneously to both ears²⁷ and added a second funnel which enabled the instrument to pick up sounds coming from two distinct areas of the body and listen to them simultaneously. There is no evidence that Purkyně, who had already constructed an instrument similar to the opistophone in the 1840s, was familiar with Alison’s apparatus, although both authors were clearly inspired by Charles Wheatstone’s earlier experiments with audition.²⁸ Despite similarities in their construction, the apparatuses were intended to serve different purposes: while both authors used them to formulate theoretical observations about binaural audition, Purkyně’s experiments went further in pursuing a theoretical understanding of spatial hearing. Alison believed in the medical application of the differential stethoscope and focused on the interpretation of the sounds heard through the instrument.²⁹ Purkyně, in contrast, was interested in hearing diagnostics and his work, which combined research in the behaviour of sound and its perception by the ear, falls under the rubric of psychophysics. In his various uses of the opistophone, hearing became both the object of knowledge and an epistemic instrument.

The term psychophysics was coined by the German physicist and philosopher Gustav Fechner in his book Elemente der Psychophysik as late as 1860.³⁰ The psychophysical investigation of hearing sought to determine the quantifiable relationship between external acoustic stimuli and their reception by the ear. Purkyně did not use the term ‘psychophysics’ but described his experiments in audition as physiological acoustics. As I will further demonstrate, however, he was concerned with both the physiological (anatomical, biological) and psychological aspects of hearing, this focus most visible in his work on auditory attention and sensory training.

Jan Purkyně referred to his physiological-acoustic experiments in the meeting of the Royal Bohemian Society of Sciences already in 1858.³¹ His main concerns were, it seems, auditory attention and spatial hearing. The purpose of the experiments Purkyně briefly described was to determine how speech sounds were perceived when different words were coming to each ear at the same time. Purkyně and his assistants pulled two long rubber tubes (Doppelhörrohrs) through two holes drilled in a door. Two people then spoke simultaneously into the speaking funnels at one end, while in the other room the ends were firmly attached to the outer auditory canals of both ears. It was observed that the voices did not blend into each other and that auditory attention could not be paid to both sounds at the same time but jumped alternately from one to the other. In these initial experiments, attention was defined physiologically – even if one made a significant mental effort, it was very hard, if not impossible, to focus on both sounds.

During the experiment, Purkyně noted yet another significant phenomenon: when the sounds were arriving at both ears at the same time, they were not heard in front of the listening subject, where the source of the sound was located, but in the back of the head, close to the neck. Only when they came separately were they heard exclusively in one or the other ear. This was a phenomenon, Purkyně explained to the Royal Society, which merited further investigation.³²

A detailed account of these experiments was given in the Czech natural-scientific journal Živa the following year.³³ Purkyně tried to make all kinds of modifications to learn more about the factors that objectively influenced hearing experience: When one of the tubes was interrupted by pressing it in the middle, for example, the sound moved from the back of the head either to the left or the right side. When one of the hearing tubes was shorter, the sound was heard on the shorter side, provided that there was only one speaker. When there were two speakers, and the one talking into the longer tube spoke louder, the sound was heard in the back of the head again!³⁴ However, when there was a kautschuk sphere in the middle of the tubes to collect the sounds, the length of the tubes became irrelevant – the sphere itself turned into the sound source. Purkyně did not stop there, though, and conducted an additional round of experiments in which he attached side tubes with funnels to the original tubes by means of small kautschuk spheres and observed how the sensation of sound changed.³⁵

This was experimental physiology as Purkyně imagined it. Besides their theoretical value, the experiments had their practical application as well. As already noted, if the speaking funnels were brought to touch each other and only one voice spoke into them, the sound was always heard in the back of the head. If the sound was heard on one side only, it served as evidence of impaired hearing, which Purkyně further examined using additional rubber tubes.³⁶ The principle was similar to that of Erns Heinrich Weber’s standardized hearing test, in which vibrating tuning forks were used instead of hearing tubes.³⁷

Apart from pre-existing hearing impairment, Purkyně observed another three circumstances that could impact the result of the experiment: (1) any difference in the size and length of the tubes; (2) excessive loudness of the voice; and (3) having one’s eyes open during the experiment. Visual information, Purkyně explained, was so ‘overwhelmingly powerful’ that the subjects tended to ignore their subjective sensations and were compelled to connect the sounds to what they saw, and thus reported that they heard them in the front.³⁸

4. Exploring auditory attention: the Ear of Dionysus, and the gymnastics of hearing

As explained in Živa in 1859, Purkyně’s intention to write a full-length monograph on hearing dated back to at least 1825. After the publication of his famous works on subjective vision, including the Beobachtungen und Versuche zur Physiologie der Sinne, he started to work on hearing, but – preoccupied by teaching in Breslau at the time – discontinued his research before he was able to gather enough material for publication. It seems that Purkyně performed the basic double tube hearing experiments in Breslau as early as 1845. Following in the footsteps of Charles Wheatstone, he set up experiments to further explore spatial hearing, especially as regards the ability of the ear to localize the sound source.³⁹ He did not pursue the topic further, however, and when reflecting back on his listening experiments after returning to Prague more than a decade later, he could no longer remember why he had dropped this strand of research.

We can find a more elaborate description of the state of Purkyně’s hearing experiments in documents of the Royal Bohemian Society of Sciences from July 1860. As for the experiments with the double tube and auditory attention, he specified that he had employed two people to utter different sentences in Czech and German into the funnels, but with the same number of syllables and in a similar voice. Purkyně put himself in the position of the experimental subject⁴⁰ and observed how his attention behaved: ‘At first I listen equally to both sides. I couldn't distinguish anything clearly.’ After a few repetitions, however, he was able to pay attention either to the left or the right ear and clearly distinguish German and Czech sentences. To find out more, he designed and constructed a more sophisticated instrument:

I took a long cylindrical box made of cardboard; in that, ten holes were made evenly in which as many short glass tubes were inserted. In each glass tube, a rubber tube (Kautschukröhr) was inserted with a funnel (Trichter) at the free end. Two small tubes were then put in one end of the box, which were connected with my two auditory canals by communication tubes.⁴¹

I let just as many voices speak into the 10 funnels at once and listened to this Babylon. It takes a pretty strong brain not to become mad. I soon gave up trying. Despite the most strenuous attention I was not able to find any meaning in this tangle of voices, which also resounded loudly inside of my head. I would call the instrument the ear of Dionysius and recommend it at most as a means of punishment.⁴²

Purkyně believed, though, that the listening subject would eventually learn to understand the words if the experiment was divided into successive stages and allowed him some time to gradually attain some listening skill. He called this the ‘gymnastics of hearing’ (Gymnastik des Gehörs).⁴³ Around 1860, the idea of sensory training thus became a salient feature of Purkyně’s research into audition and as such it represents an interesting link to Erns Mach’s work on the accommodation mechanism of hearing from the 1860s and 1870s. Similarly to Mach, Purkyně came to believe that auditory attention was not given only physiologically, but could also be trained and cultivated.⁴⁴ The understanding of auditory perception as a combination of psychological effort and material and physiological conditions underscores the psychophysical nature of Purkyně’s work on hearing. Unlike Mach, Purkyně did not elaborate on the historicity of listening in the context of musical aesthetics, but, similarly to him, he sought experimentally to determine the psychophysical grounds of auditory attention.

There is no direct evidence of whether Mach was influenced by Purkyně’s work in audition. Apart from a letter in Purkyně’s correspondence from 1867, in which Mach asks to borrow the model of the Organ of Corti to use it in a demonstration of auditory perception,⁴⁵ and the similarity of their hearing experiments with long rubber tubes going from one room to another,⁴⁶ there are only indirect indications showing similar interest in the parameters of the subjective perception of acoustic phenomena.

In her seminal study on psychophysical research on hearing, Alexandra Hui defined the nascent field in terms of a combination of experimental and natural-scientific methods and a profound interest in subjective sensory experience, mostly with respect to musical listening.⁴⁷ A direct consequence of the growing interest in subjective audition, which came to be understood as the only gateway to the study of sound sensation, was a renewed emphasis put on self-experiment as a standard epistemic practice. In psychoacoustics, the boundary between experimental subjects and objects became increasingly fluid as subjective perception itself became the object of analysis.⁴⁸ A similar principle can be found in Purkyně’s work in audition, which, as described above, routinely began with him in the position of experimental subject. Self-experimentation, however, often represented only the first step of analysis, which helped to define the research problem to be further examined under different experimental conditions. The phenomenon thus identified was subsequently tested with other subjects, as was the case, for example, with the inmates of the Prague Institute for Deaf-Mutes.

In contrast with the psychophysical research in audition described by Hui, musical aesthetics was not the main point of departure for Purkyně. Although he appreciated the art of music and designed several experiments with musical tones and instruments,⁴⁹ it was primarily the perception of speech he was interested it. He tested the capacity of the ear to discriminate the sounds of specific vowels and consonants, syllables, words, and sentences, both in Czech and in German. Unlike most other scholars researching sound perception in the nineteenth century, Purkyně did not work with tuning forks,⁵⁰ or other ready-made acoustic instruments,⁵¹ but – making use of cardboard, glass, rubber, metal wires, and wood – he designed his own research instruments, ones that would meet his specific experimental needs.⁵²

5. The birth of the binaural listener

As late as 1879, the German physicist Anton Steinhauser remarked that, to his knowledge, there existed no study of binaural audition that would develop a theoretical understanding of hearing performed with two ears.⁵³ This observation was, however, incorrect and the fact that Steinhauser made no references to earlier research of the subject in his book testifies more to the limited scientific attention paid to the study of binaural hearing before the late 1870s. In other words, the idea of the binaural listener, along with the concept of auditory space, emerged only gradually from a complex network of scientific, cultural, and technological practices during the nineteenth century.

The capacity of hearing to determine the position of a sound source had already been investigated by Giovanni Battista Venturi and William Charles Wells in the late eighteenth century, and a similar avenue of research was pursued by Charles Wheatstone and the Weber brothers, Eduard and Ernst Heinrich, in the first half of the nineteenth century.⁵⁴ In recent historiography, advances in the study of binaural audition have been connected with inventions of scientific instruments in the nineteenth-century, such as Anton Steinhauser’s homophone or the so-called pseudophone designed by the English physicist and engineer Silvanus P. Thompson in 1879.⁵⁵ Purkyně’s opistophone, constructed already in the 1840s, is usually missing from the historiography of binaural hearing. Both Steinhauser’s experiments, in which he covered his eyes and plugged his ears with different materials to examine the parameters of spatial hearing, and Thomson’s attempts to formulate a complex theory of audition employed, however, experimental principles and ideas very similar to those applied by Jan Purkyně more than two decades earlier and confirmed Purkyně’s earlier observation that the two ears work together in an intricate way to perceive sound in space.

Scholars such as Jonathan Crary, Nicholas Wade, and, most recently, Gascia Ouzounian have observed that the 19th–century understanding of binaural audition was modelled on earlier theories of binocular vision.⁵⁶ Binaural scientific instruments were fashioned on existing binocular apparatuses such as the stereoscope and pseudoscope, and the perception of sound was routinely compared to that of colour. The binaural listener thus resembled the earlier binocular viewer.

The visual basis of sensory perception in scientific theories was reflected not only in the language used, but also in the general preference of seeing over hearing as regards both its capacity to perceive space and its general value as an epistemic instrument in the sciences.⁵⁷ For Purkyně, too, vision was the most objective and analytical of the senses, a primary instrument of science and mechanical and geometrical knowledge. Hearing was indispensable for the development of language, but where it was most appreciated by Purkyně was in the context of music.⁵⁸ By the early 1850s, he seems to have fully subscribed to the idea that hearing was naturally linked to emotion and unfit to serve as an instrument of scientific inquiry.⁵⁹ In order for musical tones and speech sounds to be scientifically quantifiable, they had to be imagined as waves and vibrations; that is, they had to be visualized.

Purkyně’s early experiments with sound images testify to his privileging of vision in the sciences. To assume, however, that the psychoacoustic experiments he performed in the later stages of his career derived from his earlier work on vision would be a misconception. Although it was mostly in the context of his long-term investigation of human vision that he developed a more systematic approach to the senses,⁶⁰ Purkyně’s basic understanding of perception, which posited the existence of shared objective causes of both hearing and vision, derived from his early work on sound and assumed oscillations and vibrations to be the basis of subjective perception.⁶¹ As already pointed out, Purkyně’s experimental research on the senses was conducted against the background of his natural-philosophical thought and there was a constant feedback-loop between the scientific and metaphysical parts of his work. This is not to say that Purkyně’s experiments in audition resulted directly from his earlier writings on acoustics and perceptual unity, as it represented a different and more empirical strand of his research; rather, his philosophical and experimental understanding of seeing and hearing were related in a more complex way than traditionally assumed. Such conceptual connections – which became best articulated in his theoretical reflections on the relationship between subjective and objective knowledge – make it problematic to claim that Purkyně’s research on hearing simply reproduced insights from his visual experiments.

Purkyně clearly privileged seeing over hearing as far as analytical knowledge was concerned. Nonetheless, without explicitly elaborating on the analytical value of hearing, in his psychophysical experiments, hearing became both an object and a tool of scientific investigation. I emphasize this double role of hearing to underscore a more general divide between scientific discourse on the epistemic validity of senses, in which seeing was clearly privileged over hearing throughout the period, and the involvement of embodied knowledge in scientific practice, in which senses other than vision were also employed as reliable instruments of inquiry.⁶² Although hearing was considered secondary to vision in the perception of space, distance, and direction, Purkyně was keen on investigating the parameters of objective auditory knowledge and its relationship to subjective hearing phenomena. It was through his own and his test subjects’ listening experience that he was able to arrive at a better theoretical understanding of human audition.

All sensory perception, Purkyně repeatedly argued, oscillated between two ends: the distinct ‘objective’ sensations of the external world and the internal subjective experience (sometimes at the edge of pain and irritation of the mind). Subjective sensations, Purkyně was convinced, came before one could interpret and objectively perceive the phenomena:⁶³ in hearing, loud sounds such as shooting, banging, drumming, but also creaking or bell ringing, were perceived as less objective, as they were subjectively experienced as resounding inside the skull, and it was hard to associate them with the original sound source. Purkyně classified such kinds of auditory perception under the rubric of what he called organic subjectivity. As I will further argue, the concept of organic subjectivity created a new theoretical space in which both the objective grounds of sensory perception and its subjective nature could be considered together.

6. The hearing deaf and organic subjectivity

One morning, a man brought his son, who was about seven years old, to professor Purkyně for an examination of his hearing. The boy was deaf and dumb but had an ‘alert mind’ and could read his father’s lips very well and thus understand his speech. At first, he found it difficult to do the same with Jan Purkyně, but, after a little practice, he could also understand the words the professor was saying. When his father was invited to talk to his son through the double hearing tube, the boy could hear and – which was surprising – also understand all the words, even though the man’s mouth and most of his face were covered by the funnel. Although some words required repeated hearing to be understood by the boy, ultimately, he was able to connect the sounds to the language as he knew it. But how did he make these associations?

To find out more about how the deaf and hard of hearing experience audible language, Purkyně made similar experiments at the Prague Institute for deaf-mutes. In order for the experiments to be effective, two conditions had to be met: (1) some hearing had to remain in the children under examination and (2) they had to be at a certain (unspecified) degree of mental development, otherwise the experiments were too laborious and likely to end in failure.⁶⁴

When listening through the opistophone, the reports said, even people ‘completely deaf’ could suddenly hear the applied speech sounds. Unlike the seven-years-old boy, however, most could not understand the spoken language, as they only recognized the words visually, by reading the speakers’ lips and were not able to associate the sounds with the movements of the lips when they could not see them.

As a matter of fact, the opistophone did not restore hearing in the deaf. It is important to point out that the term deaf (or Taub in German) was used rather vaguely in nineteenth-century sources, denoting also those who were hard of hearing, and that no systematic difference was made between various kinds or degrees of hearing disability. Therefore, the term did not necessarily signal complete physiological deafness and was not used in a strictly defined medical or physiological sense.⁶⁵ To put it differently, one could be deemed deaf in his daily life or in the context of institutional education, but hard of hearing by the nascent otological standards, such as when a person’s hearing was tested in an experimental setting using the opistophone. Purkyně’s experiments were part of the process of establishing such audiometrical standards. When describing his work with the ‘deaf’ in 1859, Purkyně recalled that during his visit to the Taubstummen-Institute, he was shown that many deaf people could hear the sound of a whistle or louder sounds in general, which was one of the reasons why he asked to conduct experiments on the inmates.

Purkyně performed additional experiments on the seven-year-old boy. Not only was the boy (whose name is never given) asked to listen to words and understand their meaning, but also to differentiate between tones and recognize pitch. First, he had to watch when notes were struck on drinking glasses and count them out loud. Then the experiment was repeated with his face turned away. The boy succeeded in both parts, indicating the tones by pointing towards either a small glass (for higher tones) or a large glass (for lower tones). Finally, he attempted to repeat sounds of different pitch with his own voice, which he managed to do with some mistakes and omissions. However promising the initial results appeared, Purkyně admitted to his colleagues in the Royal Bohemian Society of Sciences that similar attempts failed with other boys, who ‘always gave the same tone, albeit weaker or stronger depending on the perceived loudness’.⁶⁶ As far as the perception of language was concerned, Purkyně observed that the deaf who could not hear any speech sounds by the naked ear were puzzled by the sounds coming to them through the tubes, which they could repeat in an untrained voice, yet without recognizing their meaning.⁶⁷

The main theoretical research question behind these experiments was: How can a deaf-mute (taubstumme) but weakly hearing (schwach Hörende) person understand spoken language?⁶⁸ The answer Purkyně arrived at was relatively simple: by hearing his own voice. Drawing on his many experiments, he concluded that people did not hear their own voice primarily from the outside, as it comes to the ears through the air, nor even exclusively through ear trumpets, in which the closed off voice also resounds strongly, but primarily through the medium of their solid body parts (that is, the jaw, skull and throat).⁶⁹ As Purkyně wrote in Živa in 1859, sounds transported through the skull were of a subjective nature, because they were determined by the volume of the skull and the physical constitution of the listening subject. These were neither auditory hallucinations nor memory images but results of the interaction between individual perception and objective acoustic phenomena.⁷⁰ Purkyně called this organic subjectivity. The concept enabled him to consider both external acoustic impressions (the objective stimuli) and their perception by the ear in one physiological framework. Purkyně’s organic subjectivity was not completely identical with the idea of psychophysiology soon to be introduced by Gustav Fechner, as it paid more systematic attention to the variability of individuals’ physiological constitutions and to the nature of their relationships to sound sensation. As already noted, in his understanding of ‘physiological acoustics’, Purkyně came to recognize the psychological dimension of perception and the role of sensory training and experience in the ability to register and interpret sounds. The concept of organic subjectivity offered another layer of sophistication to the study of sensory perception: not only was it moulded by experience, but its physiological underpinning was also – to a certain degree – subjective. It was in such an epistemic framework that Purkyně examined the parameters of audible language in the deaf and hard of hearing.

In line with the oralist method of teaching deaf-mutes in the nineteenth century,⁷¹ when children whose hearing was impaired first learned to speak, they were asked to repeat the words spoken to them out loud. As such, they came to associate the speech with what they heard inwardly, when they themselves were trying to pronounce the words. It should not come as a surprise, then, concluded Purkyně, that they had some understanding of audible language when later assisted with hearing aids. What they had to learn was to integrate the two heard languages into one and compare the speech sounds heard through the opistophone to their own manner of speaking.⁷²

Such ‘endocephalic’ hearing inside one’s skull was examined already in the initial experiments with hearing tubes, in which Purkyně observed that sounds were subjectively perceived in different parts of the head. To examine this further, he had another instrument made in 1860. This comprised a tiny hollow rubber sphere (hohlkugel), 1½ inches in diameter and as firm as possible, which was drilled in three places, and three glass tubes with rubber tubes attached to them, which were inserted into the holes. One rubber tube was then placed in the ear, while the other two were connected to funnels and used for speaking. The experiment suggested that auditory impressions were influenced by the positions of vowels in a sentence: whereas the simple vowels (a, e, i, o, u) merged in all combinations, they behaved differently when combined with s, š, z, ž, and w, on the one hand, and k, t, and p, on the other.⁷³ Additional tubes could then be added to the instrument so that, finally, it would become the Ear of Dionysus from his initial experiments.

To experiment with different tones, Purkyně made two 7 ½-inch-long wooden labial pipes with removable stoppers, which were attached to the ear by a tube. The tones from each pipe could be heard very distinctly and – depending on the difference in their interval – were accompanied by the corresponding (and very strong) combinationstöne, which were heard in the rear half of the skull endocephalically. After both ears were connected to the sphere, the third tone sounded clearly inside the occiput in the way already observed in the Doppelhörrohres experiments.⁷⁴

Purkyně’s systematic examination of intracranial sounds was a pioneering attempt at the experimental investigation of the phenomena. The nature of these subjective auditory impressions, also referred to as ‘acoustic images’, was later examined by Silvanus Thompson and the otologist Viktor Urbantschitsch.⁷⁵ The question of whether such impressions were of psychological, physical, or physiological origin prefigured psychoacoustic debates in the last decades of the nineteenth century.⁷⁶ In this respect, Purkyně’s concept of organic subjectivity offered a conceptual framework in which all these aspects of hearing could be fruitfully examined together.

7. Conclusion

Experimenting with different designs of the opistophone, Purkyně sought to investigate the parameters of spatial hearing and the nature of subjective auditory experience. The different material conditions, instruments, and set-ups of the experiments reflect both the empirical and theoretical radicality of Purkyně’s physiology project. Although largely neglected by historians, his work on audition fits into the wider framework of the development of psychoacoustics in the nineteenth century and represents an original early attempt at pinning down the exact relationship between the objective and subjective aspects of perception.

The significant shift observable in Purkyně’s work is the one from a physiological to a psychophysical understanding of attention. His notion of the ‘gymnastics of hearing’ testifies to the evolution of his theoretical understanding of audition, which was reflected also in his experiments with the inmates of the Prague Taubstummen-Institut in the late 1850s. Purkyně’s study of intracranial hearing and bone conduction in the deaf and the hard of hearing represents the pinnacle of his work on human audition and epitomizes his understanding of the relationship between individual perception and objective acoustic phenomena. Both in terms of the research questions posed, the results obtained, and the material conditions of the investigations, many of the opistophone experiments foreshadowed later psychoacoustic investigations, such those of Ernst Mach, Anton Steinhauser, and Silvanus Thompson. Purkyně’s theoretical understanding of audition was best articulated in his notion of organic subjectivity, which created a conceptual space in which interactions between the physical, physiological, and psychological facets of hearing could be examined. It is not only the materiality of his experiments, but also their theoretical underpinning by the concept of organic subjectivity which represent significant degree of epistemic continuity between Purkyně’s work in audition and later developments in the psychophysical understanding of hearing.

Although Purkyně’s work on subjective vision became standard reading for those working on sense perception in the first half of the nineteenth century, his experiments in audition never gained the same degree of prominence. This neglect, both historical and historiographical, might stem partly from the fact that Purkyně examined the subject later in his career and never wrote a full-length German study on the topic. He gave accounts of his experiments in German to the Royal Bohemian Society of Sciences but described them in more detail in his Czech articles in Živa. One might speculate that if Purkyně had had more time to perform additional experiments he would eventually have gathered enough material for the publication of a German monograph on the topic, as he had intended to do early in his career. It seems, however, that gaining prominence in German-speaking Academia was no longer a priority in the last two decades of his life, when he was much more concerned with the political and cultural position of the Czech nation in the Austro-Hungarian Empire. The systematic fostering of Czech scientific culture – i.e. work produced by Czech scholars, written in the Czech language, and accessible to a wider readership – became Purkyně’s personal mission after his return to Prague in 1850 and it is probably in this light that we should interpret his motivation to publish his research in Živa. The extent to which his work both influenced and reflected wider sonic investigations in Bohemia in both academic and non-academic fields, including psychophysiology, pedagogy, and phoniatrics, but also musicology and fine arts, merits further research.

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No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Czech Science Foundation: [grant number 20-30516Y].

Notes

1 The Institute was founded in 1786; for most of the 19th century it was known under the German name Prager Taubstummen-Institut, or Pražský ústav pro hluchoněmé in Czech. See Lenka Okrouhlíková, ‘Český znakový jazyk - pohled do historie’, Speciální pedagogika, 25 (2015), pp. 278–298.

2 Jan Evangelista Purkyně, Jana Ev. Purkyně korespondence I., ed. by J. Jedlička (Praha: Unie, 1920), pp. 135–136.

3 Purkyně, Korespondence, pp. 136–137.

4 This information also appears in the minutes of the 37^th meeting of Deutscher Naturforscher und Ärzte in Karlsbad (Section: ‘Anatomie und Physiologie’), September 22, 1862, see Jan Evangelista Purkyně, Opera Omnia, Tomus III (Praha: Purkyňova společnost, sdružení pro studium osobnosti a díla J.E. Purkyně, 1937), p. 117.

5 The name opistophon appears in the reports from the meeting of Deutscher Naturforscher und Ärzte (1862), Purkyně, Opera Omnia III, 118.

6 In the last two decades, historians of science and media have increasingly emphasized the role of the senses other than vision in the development of Western science and epistemology. The now well-established field of ‘sound studies’ has posited a variety of associations between sound, hearing and knowledge in the modern era, and called for a re-evaluation of the relationship between the aural and the visual in the historical practices of knowledge production; see Jonathan Sterne, The Audible Past (Durham & London: Duke University Press, 2003), and Trevor Pinch and Karin Bijsterveld, eds., The Oxford Handbook of Sound studies (New York: Oxford University Press, 2013).

7 The best current discussion of the ‘sonic turn’ in France and the German-speaking world can be found in Viktoria Tkaczyk, Thinking with Sound. A New Program in the Sciences and Humanities around 1900 (book manuscript, forthcoming with the University of Chicago Press). Among the disciplines concerned with sound, Tkaczyk mentions psychophysiology, linguistics, phonetics, neuroanatomy, pedagogy, musicology, phoniatry, architectural acoustics, and shock wave physics. See also Viktoria Tkaczyk ‘Whose larynx is it? Fields of scholarly competence around 1900’, History of Humanities, 3 (2018), pp. 57–73; Alexandra Hui, The Psychophysical Ear: Musical Experiments, Experimental Sounds, 1840–1910 (Cambridge, MA/London: The MIT Press, 2013); Benjamin Seege, Helmholtz and the Modern Listener (Cambridge: Cambridge University Press, 2012); Julia Kursell, Epistemologie des Hörens: Helmholtz' physiologische Grundlegung der Musiktheorie (Paderborn: Fink, 2018); Myles W. Jackson, Harmonious Triads: Physicists, Musicians, and Instrument Makers in Nineteenth-Century Germany (Cambridge MA: The MIT Press 2006); Axel Volmar, Klang-Experimente: Die auditive Kultur der Naturwissenschaften 1761–1961 (Frankfurt am Main: Campus, 2015); Veit Erlmann, Reason and Resonance: A History of Modern Aurality (New York: Zone Books, 2010).

8 See Hui, pp. 89–122.

9 The only notable exception is Martha Brech, Der Hörbare Raum: Entdeckung, Erforschung und musikalishe Gestaltung mit analoger Technologie (Bielefeld: Transcript, 2015), pp. 38–44. Veit Erlmann mentions Purkyně’s discussion of the subjective hearing experience of Tartini’s combination tones but does not deal with his later experiments in audition, see Erlmann, pp. 207–211.

10 For general overviews of Purkyně’s scientific activities in English see F. K. Studnička, ‘J. E. Purkinje's "Physiology" and His Services to Science’, Osiris, 2 (1936), pp. 472–483; J. John Henry, ‘Jan Evangelista Purkyně: Czech Scientist and Patriot (1787-1869)’, Proceeding of the Royal Society of Medicine (1959), pp. 933–940; Vladislav Kruta, J.E. Purkyně (1787-1869) Physiologist: A Short Account of his Contributions to the Progress of Physiology with a Bibliography of his Works (Prague: Academia, 1969); see also Siegfried Zielinski, Deep Time of the Media: Toward an Archaeology of Hearing and Seeing by Technical Means (Cambridge, MA: MIT Press, 2006), pp. 193–203. The best comprehensive overview in Czech remains Eliana Trávníčková, ed., Jan Evangelista Purkyně. Život a dílo (Prague: Avicenum, 1986).

11 Purkyně's dissertation, Beiträge zur Kenntniss des Sehens in subjektiver Hinsicht, came out in Prague in 1819 and then again in 1823, see Opera Omnia I (Praha: Spolek českých lékařů, 1918). The English translation of the dissertation can be found in Nicholas Wade and Josef Brožek, Purkyně’s Vision: The Dawning of Neuroscience (Mahwah, NJ: Lawrence Erlbaum Associates, 2001).

12 The young Czech scholar was appointed against strong opposition from the members of the Medical Faculty in Breslau, see Jan Franta ‘Jan Evangelista Purkyně – významná životopisná data’, Živa 5 (2011), pp. 198–199.

13 Apart from becoming the chair of the new Physiological Institute, Purkyně became a member of the Academy of Sciences in Berlin (1832); this was followed by membership of the Royal Society in London (1850) and the Academy of Sciences in Vienna (1860). He was also a corresponding member of the Academies of Sciences in St. Petersburg. (1836) and Paris (1861). In 1824, he entered the Silesian Society for Patriotic Culture (Schlesische Gesellschaft für Vaterländische Kultur), where he delivered regular reports about his work until 1850. See Jan E. Purkyně, ‘Autobiografické stati a bibliografie’, in Opera Omnia, XVIII, ed. by Vladislav Kruta and Vladimír Zapletal (Praha: Academia, 1985).

14 See K. Aterman and Eliana Trávníčková, ‘Purkyně’s Heautognosis’, Medical Biography 9 (2001), pp. 87–96; John, pp. 933–940; Purkyně’s overview of his experiments with different senses can be found in Jan Evangalista Purkyně, ‘Místopis čili topologie smyslů vůbec’, Živa 7 & 12 (1853), pp. 193–196; 361–365.

15 See Aterman and Trávníčková, ‘Purkyně’s Heautognosis’, p. 89. Despite his criticism of the method of self-experiment, Goethe repeatedly praised Purkyně’s work on perception; see the discussion further in this chapter.

16 Historical theories of the propagation of sound are discussed in more detail in Anna Kvicalova, Listening and Knowledge in Reformation Europe: Hearing, Speaking and Remembering in Calvin’s Geneva (Cham: Palgrave Macmillan, 2019), pp. 221–230. For Aristotle’s notions of sound, see Aristotle, De Anima, II. 8 and III. 2; De sensu, in Greek Musical Writings II: Harmonic and Acoustic Theory, ed. by Andrew Baker (Cambridge: Cambridge University Press, 1990), pp. 66–84.

17 The gradual establishment of the notion of sound as a spatial phenomenon in the 19th and 20th centuries is discussed in Brech; Paul Théberge, Kyle Devine, and Tom Everrett, Living Stereo: Histories and Cultures of Multichannel Sound (New York: Bloomsbury Academic, 2015); and, most recently, Gascia Ouzounian, Stereophonica: Sound and Space in Science, Technology, and the Arts (Cambridge, MA/London: The MIT Press, 2020).

18 See Jackson, Harmonious Triads, pp. 14–44; Zielinski, pp. 179–80, 194–203; Erlmann, pp. 155–6, 189–94.

19 Purkyně used black mercuric sulfide, which was fixed with a white precipitate. See Emil Skramlik and Miloš Kopecký, ‘Purkyňův pokus o analysu zvuku’, Československá fysiologie, 5 (1956), pp. 401–406.

20 Purkyně visited Goethe in Weimar in 1822, and Goethe wrote an extensive commentary on Purkyně’s dissertation on subjective vision. They exchanged letters until Goethe’s death in 1832. See Wade and Brožek, p. 29; Vladislav Kruta, The Poet and the Scientist: Johann Wolfgang Goethe - Jan Evangelista Purkyně (Prague: Academia, 1968). For Purkyně’s visualization of sound in the context of the German Naturphilosophie and Goethe’s work on synaesthetic perception, see Lada Hubatová-Vacková, ‘Vnitřní zrak Jan Evangelista Purkyně, laboratoř vizuality a moderní umění’, Umění, 53 (2005), pp. 566–585.

21 The notion of sound and acoustic vibrations as universal elements that represent the relations between the internal Innenwelt and the external Umwelt is discussed in Zielinski, pp. 179–203; and Erlmann, pp. 151–184. See also Hubatová-Vacková.

22 Purkyně’s philosophical ideas are best summarized in his work Papierstreifen aus dem Portefeuille, but they frequently appeared also in his lectures and articles published in the journal Živa. The relationship between his experimental and philosophical work is briefly discussed in Jan Janko, ‘Naturfilozof J. E. Purkyně’, Živa 5 (2011), pp. 206–208.

23 See Oldřich V. Hykeš, ed., Přírodovědné práce J.E. Purkyně v zrcadle kritiky jiných badatelů/Ce quie a été ecrit sur les travaux scientifiques de J. E. Purkyně per les biologistes (Prague: Knihtiskárna Jednoty československých matematiků, 1928), p. 7

24 The cubit was a measure of length, equal to the length of a forearm (usually about 44 cm). The hearing aid was thus approximately 110 cm long.

25 Despite the largely theoretical goals of Purkyně’s experiments, there are several indications that his interest in hearing aids was more profound than his reports to academic societies might suggest. In Purkyně’s correspondence from 1866, for example, a letter from his Hungarian colleague, professor Josef v. Lenhossék, can be found, in which he approached Purkyně as the utmost expert in the field of hearing aids, in which he had ‘knowledge and experience like nobody else’. Lenhossék gave a rather detailed medical account of his hearing impairment and inquired about an instrument Purkyně mentioned at a meeting of Hungarian doctors and naturalists in 1865. Purkyně, Korespondence I, 151–152.

26 Somerville Scott Alison, ‘On the Differential Stethophone, and Some New Phenomena Observed by It’, Proceedings of the Royal Society of London, 9 (1857–1859), pp. 196–209. See also Sterne, pp. 111–12.

27 The stethoscope was invented by René Théophile Hyacinthe Laennec (1781–1826); R. T. H. Laennec, Traité de l'Auscultation Médiate (Paris: Chaudé, 1819). See also Nicholas J. Wade and Diana Deutsch, ‘Binaural hearing—Before and after the stethophone’, Acoustics. Today, 4 (2008), pp. 16–27. Laennnec’s auscultation technique in medicine and its relationship to the acoustic explanation of auscultation by Joseph Škoda is discussed in Jens Lachmund, ‘Making Sense of Sound: Auscultation and Lung Sound Codification in Nineteenth-Century French and German Medicine’, Science, Technology, and Human Values, 24 (1999), 419–450.

28 The impact of Wheatstone’s work on the 19th-century understanding of binocular and binaural perception is reviewed in Nicholas J. Wade, ‘Early Studies of Binocular and Binaural Directions’, Vision, 2 (2018), pp. 1–15; and Nicholas J. Wade, ‘The disparate histories of binocular vision and binaural hearing’, Journal for the History of Neurosciences, 27 (2018), pp. 10–35 (pp. 19–21). For Wheatstone’s hearing experiments, see Charles Wheatstone, ‘Experiments on audition’, Quarterly Journal of Science, Literature and Art, 24 (1827), pp. 67–72.

29 Somerville Scott Alison, The Physical Examination of the Chest in Pulmonary Consumption and Its Intercurrent Diseases (London: John Churchill, 1861).

30 Hui, p. xv-xvi.

31 ‘Hr. Purkyně machte eine Mittheilung einiger physiologisch-acustischen experimente’, Sitzungsberichte der Königliche böhmischen Gesellschaft der Wissenschaften in Prag, October 18, 1858 (Naturwiss-mathem. Section), in Purkyně, Opera Omnia III, 99.

32 Purkyně, Opera Omnia III, 99.

33 Jan Evangalista Purkyně, ‘Zkoušky o sluchu’, Živa, 4 (1859), pp. 261–267 (p. 266).

34 The relationship between different sound intensities and the ability of the ears to determine the position of the sound source was later discussed by the physicist Anton Steinhauser, See Anton Steinhauser, ‘The theory of binaural audition. A contribution to the theory of sound’, in Philosophical Magazine 7, trans. Silvanus P. Thompson (1879), pp. 181–197 (p. 186).

35 Purkyně, ‘Zkoušky’, p. 266.

36 Purkyně, ‘Zkoušky’, p. 266. The same application is mentioned in Purkyně’s lecture on auditory sensations in the occiput delivered to the Royal Bohemian Society of Sciences on July 4, 1860, see Jan- E- Purkyně, ‘Hr. Purkyně sprach über seine Versuche über die Coinsidenz gleicher Gehörempfindungen im Hinterhaupte’, in Purkyně, Opera Omnia III, pp.102–105 (p.104).

37 In 1834, Ernst Heinrich Weber used the vibrating tuning fork placed on the patient’s forehead as a means to diagnose one-sided conductive hearing loss. For the so-called Weber test, see Myles Jackson, ‘From Scientific Instruments to Musical Instruments’, in Pinch and Bijsterveld, pp. 201–223 (p. 205).

38 Purkyně, Opera Omnia III, p. 104; Purkyně, ‘Zkoušky’, p. 266.

39 Purkyně was familiar with Wheatstone’s work on perception. In the first experiments with spatial hearing and the localization of sound he performed in Breslau in 1845, Purkyně took direct inspiration in Wheatstone’s experiments in audition, see Purkyně, ‘Zkoušky’, p. 262. He also mentions Wheatstone’s binocular stereoscope in the review article ‘Podrobné zprávy o mojích starších I novějších literárních, zvláště přírodníckých pracech’, Živa 4 (1858), pp 242–6 (p. 243).

40 For the fluidity of the boundaries between experimental subjects and experimental objects in psychophysical research on sound, see Hui, xi-xxii. See also the discussion in Chapter 4 of this article.

41 Purkyně, Opera Omnia III, p. 102, author’s translation.

42 Purkyně, Opera Omnia III, p. 103.

43 The expression is also used in the journal of Czech physicians Časopis lékařů českých. It refers to listening exercises which people suffering from hearing disabilities should practice in order to improve their hearing; see M. Smoler, ‘Krátký rozhled v chorobách ústrojí sluchového’, Časopis lékařů českých (1865), pp. 415–416.

44 Mach’s psychophysical work on auditory attention and his accommodation experiments are best described in Hui, pp. 89–122. As early as 1863, Mach came to understand hearing as a culturally bound phenomenon and define accommodation in hearing as an altered physiological sensation brought about by a psychological change, see Hui, p. 95.

45 In 1867, Mach became the professor of experimental physics at Charles University in Prague (called Karl-Ferdinand University at that time); the letter to Purkyně can be found in Purkyně, Korespondence I, p. 154.

46 Mach’s experiment, in which he placed his assistant with a long rubber tube in his ear in one room, while he himself was singing softly into its other end in the next room, resembles Purkyně’s hearing tube experiments from the 1850s. See Ernst Mach, ‘Zur Theorie des Gehörorgans’, Sitzungsberichte der kaiserlichen Akademie der Wissenschaften, 48/2 (1863), pp. 283–300 (p. 289); the experiment is described also in Hui, p. 96.

47 See Hui. The reciprocal relationship between music and scientific investigation in the 19th and 20th centuries is examined in Alexandra Hui, Julia Kursell, and Myles Jackson, eds., Music, Sound and the Laboratory from 1750–1980, Special issue of Osiris, 28 (2013).

48 Hui, xiv.

49 Purkyně envisioned, for example, that his experiments with the opistophone could have practical implications for learning musical tones; see ‘Hr. Purkyně theilte wieder mehrere physiologisch-acustische Versuche im Folgenden mit’ (July 30, 1860), in Purkyně, Opera Omnia III, pp. 105–111 (p. 107). For his experiments with so-called Tartini tones, see the discussion in chapter 6 of this article.

50 The Weber brothers and Chladni used tuning forks as physical instruments to study sound-wave propagation. Curiously enough, Purkyně did not use truing fork even when revisiting the Weber brothers hearing experiments. See Jackson, ‘Instruments’, pp. 202–207. For Purkyně’s detailed assessment of Eduard Weber’s sound direction experiments, see his lecture on the occiput in Purkyně, Opera Omnia III, p. 104.

51 Similarly to Charles Wheatstone, S. Scott Alison, Eduard Weber or Heinrich Dove, Purkyně also briefly experimented with the sounds of the ticking pocket watch. He soon dropped the experiments, though, and moved to the perception of speech sounds instead. See Wade and Deutsch; Purkyně, ‘Místopis’, p. 194.

52 The financial records of Purkyně’s Institute suggest that he designed various experimental instruments, which he then ordered to be made for him by external mechanics with whom he cooperated in the 1850s and early 1860s. See Oldřich Vilém Hykeš, and D. E. Hykešová, ‘Pražský Fysiologický Ústav Purkyňův’, Biologické Listy, 15 (1930), pp. 44–63. I am thankful to Ivan Loginov for the reference.

53 Steinhauser, pp. 181–182.

54 See Wade and Deutsch, pp. 16–27. Purkyně met Ernst Heinrich Weber at the Congress of German Natural Scientists and Physicians in Berlin in 1828, see Franta, p. 199.

55 Both instruments are discussed in detail by Nicholas Wade in ‘Early Studies’, pp. 8–13, and ‘Disparate Histories’, pp. 19–21; and in Chapter 2, ‘The Rise of Binaural Listener: Spatial Hearing in the 19th Century’ in Ouzounian, pp.70–124.

56 See Jonathan Crary, Techniques of the Observer: On Vision and Modernity in the Nineteenth Century (Cambridge, MA: MIT Press, 1990); Wade ‘Early Studies’, and ‘Disparate Histories; Wade and Deutsch; Ouzounian, pp.76–77.

57 The strong tendency to associate seeing and visual means of representation with objective knowledge in the sciences is discussed, most notably, in Lorraine Daston and Elizabeth Lunbeck, Histories of Scientific Observation (The University of Chicago Press, 2011); and Lorraine Daston and Peter Gallison, eds., Objectivity (New York: Zone Books, 2007); see also Crary, Techniques of the Observer.

58 Jan Evangalista Purkyně, ‘O smyslech vůbec’, Živa, 6 (1853), pp. 163–168 (pp. 165–166).

59 The association of hearing with emotions, spirituality and one’s inner world in the 17^th and 18^th centuries is discussed in Leigh Eric Schmidt, Hearing Things: Religion, Illusion, and the American Enlightenment (Cambridge, MA: Harvard University Press, 2000). Media historian Jonathan Sterne talks about the modern ‘audiovisual litany’ whereby opposing qualities are systematically ascribed to sound and vision, see Sterne, pp. 15–19.

60 See Purkyně’s dissertation Beiträge zur Kenntniss; and Wade and Brožek. For a discussion of Purkyně’s theories of subjective vision, see also Jutta Müller-Tamm ‘Die Empirie des Subjektiven bei Jan Evangelista Purkinje. Zum Verhältnis von Sinnesphysiologie und Aesthetik im frühen 19. Jahrhunderts, Studien zur Geschichte visuelle Kultur um 1800’, in Wahrnehmung der Natur, Natur der Wahrnehmung. Studien zur Geschichte visueller Kultur um 1800, ed. by Gabriele Dürbeck (Dresden: Verlag der Kunst 2001), pp. 153–164.

61 See Skramlik and Kopecký; Hubatová-Vacková. Sound’s ability to articulate perceptive unity through vibrations and frequencies is discussed in Zielinski, pp. 179–203; Erlmann, pp. 151–184. Compare to Peter Pesic, ‘Thomas Young’s Musical Optics: Translating Sound into Light’, in Hui, Kursell and Jackson, pp. 15–39.

62 The fact that the epistemic role of hearing becomes visible when we shift the attention from the study of scientific results and means of representation to the study of scientific practice is discussed in Trevor Pinch and Karin Bijsterveld, ‘New Keys to the World of Sound’, in The Oxford Handbook of Sound Studies, pp. 3–35.

63 Purkyně, ‘Zkoušky’, p. 267.

64 See Purkyně, Opera Omnia III, pp. 105.

65 The vague use of the term deaf testifies to the mixing of cultural and scientific approaches to the ear in the period, when no strictly defined physiological definition of deafness was available or consistently applied. The relationship between deafness as a medical diagnosis on the one hand, and deafness as a culturally and socially negotiated category on the other is discussed in Anna Kvíčalová, ‘Hearing Difference in Calvin’s Geneva: From Margins to Center,’The Sixteenth Century Journal, 49/1 (2018), pp. 25–47. A theoretically nuanced approach to disability as a product of the interplay between the physical body and its social environment can be found in Michael Schillmeier, Rethinking Disability: Bodies, Senses, and Things (New York: Routledge, 2010).

66 Purkyně, Opera Omnia III, p. 106.

67 Purkyně, ‘Zkoušky’, p 266.

68 Purkyně, Opera Omnia III, p. 107.

69 When both ears were completely closed in the experiment, the sound from the outside was not carried by the skull to the inner years. When a brass wire was used, however, the results were different: the wire was able to transport sound effectively when attached to a sounding body (violin, fortepiano, or other instrument) by a wooden rod, or when a person put the end of the wire in between his teeth; Purkyně, ‘Zkoušky’, p. 264.

70 Memory, along with imagination and judgement, was crucial for interpreting the information mediated by the senses. Without auditory memory, Purkyně argued, it would not be possible to understand musical tones, intervals, and rhythms, or connect speech sounds into meaningful sentences; see Purkyně, ‘Místopis’, p. 166.

71 Although from the 18^th-century onwards, so-called oralism (or the ‘German method’ of Samuel Heinicke) competed with ‘manual’ approach to deaf education based on the use of sign language (the ‘French method’), oralism came to prevail in 19th-century education; see Mara Mills, ‘Deafness’, in Keywords in Sound, ed. by David Novak and Matt Sakakeeny (Durham/London: Duke University Press, 201), pp. 45–54 (pp. 47–50). In the Prague Taubstummen-Institut, a special position was developed by its director Václav Frost in the mid-19th century, who pioneered the ‘bilingual’ teaching method, which combined sign language and articulation; Okrouhlíková, p. 282.

72 ‘It is possible that with special exercise and training from their teachers, they could learn to compare the [speech] sounds to their own speech and translate one into the other. Hopefully, somebody will try to teach them.’ Purkyně, ‘Zkoušky’, 266.

73 Apart from examining speech sounds, Purkyně believed that there was further potential in experimenting with musical (as well as non-musical) instruments of different timbres, including forms of percussion; see Purkyně, Opera Omnia III, pp. 107–108.

74 Purkyně, Opera Omnia III, p. 108. So-called ‘combination tones’ (Combinationstöne) referred to the phenomenon where when two tones sounded simultaneously, a third tone, lower in pitch, was heard as well. The phenomenon was most famously examined by Hermann von Helmholtz in his 1856 Ueber Combinationstöne, but it was known long before that. The ‘third tones’ had already been investigated by the Italian violinist Guiseppe Tartini in the 18th century and are sometimes referred to as ‘Tartini tones’; see Jackson, Harmonious Triads, pp. 173–175; David Pantalony, ‘Rudolph Koenig’s Workshop of Sound: Instruments, Theories, and the Debate over Combination Tones’, Annals of Science, 62 (2005), pp. 57–82. For Purkyně’s investigation of the phenomenon, see also Jan Evangelista Purkyně, ‘Untersuchungen über den Tartinischen dritten Ton’ (1835), in Jan E. Purkyně, Opera Omnia Tomus II, (Purkyňova společnost: Prague, 1937), pp. 58–61.

75 See Sylvanus P. Thompson, ‘The Pseudophone’, London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 8/50 (1979), pp. 385–390 (p. 386); Viktor Urbantschitsch, ‘Zur Lehre von der Schallempfindung’, Pflügers Archiv, 24 (1881), pp. 574–595. For comparison to the notion of ‘auditory afterimages’ in Viennese and French psychophysiology in the late 19th and early 20th centuries, see Viktoria Tkaczyk, ‘The shot is fired unheard: Sigmund Exner and the physiology of reverberation’, Grey Room, 60 (2015), pp. 66–81 (pp.71–76).

76 See the discussion in Ouzounian, pp. 100–124.