Popular Science Monthly/Volume 43/October 1893/The Problem of Colored Audition



MUCH attention has been given lately to the subject of colored audition. It has been discussed in daily journals and in literary and scientific reviews; in medical theses, memoirs, and didactic treatises; it has figured in poetry and romance, and on the stage; it has been the occasion of many inquiries; and physiologists have occupied themselves with it and made laboratory experiments on it.

Notwithstanding all investigation, the subject is still imperfectly known and understood. It has been studied mostly from without. The details concerning the sounds and the associated colors have been carefully noted, but no one has told what colored audition is, or has made it intelligible to those who know of it only from others. We can not hope to be much more fortunate than our predecessors; but we shall direct our attention to the points they have overlooked, and shall try to describe a mental state in colored audition. Let us point out first, in order to gain a comprehensive view upon these questions, the circumstances under which a person first perceives that he has the faculty, as it has been called, of coloring sounds.

Those who for the first time hear these perceptions spoken of experience great astonishment. They can not gain a clear idea of them; the comparison of a sound with a color seems to them wholly destitute of intelligible character. Meyerbeer has said somewhere that certain chords of von Weber's music are purple. What does the phrase mean? Each of the words, taken by itself, has a meaning. We know what a chord is, and we know purple; but joining the terms with a verb and saying the chord is purple, is something we do not understand. As well say virtue is blue and vice is yellow; one is ready to ask if the construction of such phrases is not a trickery of words, which are brought into purely technical associations corresponding to no real association of thought.

Thus, to the immense majority of persons, colored audition is a riddle. This is one of the reasons why the world for a long time refused to believe in it, and treated as eccentrics those who concerned themselves with it—a skepticism which was all the more justified because the matter related to a subjective condition, the existence of which has to be accepted on the simple word of the person who experiences it.

We do not know whether we can make the true nature of this phenomenon understood, or whether we can help those who have not experienced it to conceive of it; but we hope to be able to demonstrate that it is real. Deception has generally an individual character; it is the work of one person and not of many; it gives no occasion for massed effects which are repeated from one generation to another, and in different countries. The number of persons who say they have colored audition must be taken into consideration. According to Bleuler and Lehmann, it is twelve per cent. M. Claparède, of the University of Geneva, who is now investigating the subject, writes us that of four hundred and seventy persons who answered his questions, two hundred and five, or forty-three per cent, had colored audition. Of course, this proportion can not be taken literally, for the immense majority of the persons who do not experience the phenomenon will not answer the queries for many motives, the chief of which is a kind of contempt for studies they do not comprehend. It is nevertheless true that M. Claparède has collected, without great effort, two hundred and five observations, and that that number, added to the old observations, gives a total of nearly five hundred cases. Such a mass of observations may well inspire some confidence. It may be added that each of the authors who have written on the question often has by him the observation of some friend in whom he has entire confidence; so that resistance to so many accumulated proofs becomes no longer wisdom, or even skepticism, but simplicity.

The first author who noticed the production of impressions of color by sounds was an albino doctor of Erlangen, named Sach, who in 1812 described in an inaugural thesis his own impressions and those of his sister. His observation is very complete, and contains a considerable proportion of the details which are found in later works. He died at the age of twenty-eight years, and his researches fell into oblivion. During the following years doctors and oculists, like Cornas, of Geneva, published isolated observations.

In 1873 appeared the important observations of the brothers Nussbaumer, one of whom was a student at Vienna, and the other a watchmaker; both of whom had from childhood experienced sensations of color when they heard certain sounds. When children they observed the ringing of spoons and knives tied to the ends of strings, designated the colors produced by the sounds, and communicated their impressions to each other; but they did not always agree concerning the colors of the different sounds, and long disputes ensued, of which their brothers, sisters, and friends could understand nothing. The student afterward published, under the direction of Prof. Brühl, a detailed memoir on the cases.

Six years afterward, in 1879, Bleuler and Lehmann wrote their memoir, the most complete one we possess. Both authors studied medicine at the University of Zurich; Bleuler writes concerning the origin of this work that they were talking of chemistry, when the subject of ketones coming up, Bleuler remarked that they were yellow, because there was an o in the word. Thus by a curious illusion he attributed the colors suggested by the name of an object to the object itself. His friend Lehmann, greatly astonished and not understanding the answer, asked for an explanation of it. This stimulated his curiosity, and they both proceeded to make inquiries among their relatives and friends. They published accounts of more than sixty cases.

From that time publications multiplied, and the present period is marked by investigations pursued in every direction. It now appears that colored audition belongs to a family of similar phenomena, which are sometimes grouped in one person and sometimes scattered. Colored audition is still the most frequent and best studied phenomenon, and is the single one which we intend to discuss. But a word should be said of the other forms. They differ chiefly in the nature of the impressions that are associated, and which serve reciprocally as excitants. Thus, in some persons, not sounds but sensations of taste and odor provoke the luminous impressions. These may be called colored gustation and olfaction. In others, psychical phenomena, like recollections or abstract notions, produce the same effect. One person sees colors in the months, in the days of the week, or in the hours of the day. In other persons the impression is not visual, but may belong to a different sense. It may be sonorous; in some persons the sight of colors gives a musical impression; or it may be tactile, and sight and hearing may be accompanied by mechanical sensations. In short, all imaginable combinations of different sensations may be realized.

In colored audition the impressions of color are almost exclusively provoked by speech; the sounds and noises of Nature producing the same effect only by a kind of analogy with the human voice. Speech gives him who hears it an impression of color only when the emission is full; a murmur has not the effect of the singing voice or of a reading in public; the height of the tone influences the shadings; barytone and bass voices excite dark sensations and high voices light ones. On a closer examination of the source of the phenomenon it is found that the color, while it may borrow a general tint from the timbre of the voice, and consequently from the individuality of the speaker, depends more especially upon the words that are pronounced; each word has its peculiar color, or we might rather say colors, for some words have five or six; pushing the analysis further, we perceive that the color of words depends on that of the component letters, and that it is therefore the alphabet which is colored; and, finally, that the consonants have only pale and washed-out tints, and the coloration of language is derived directly from the vowels. With a few exceptions this is true for all the subjects.

By a curious complication produced by education, the appearance of colors takes place in some persons not only when they hear the word pronounced or when they think of it, but even when they see it written. There are also persons who do not perceive the color except while they are reading. Many facts, however, seem to prove that reading is generally of no effect except as a suggestion of the spoken word, and therefore constitutes a kind of audition.

The observations on the colors of the vowels in detail are irregular and contradictory. Thus, a, red to one, is black to another, white to a third, yellow to a fourth, and so on; the whole spectrum passes through it; but as the number of colors and of letters is limited, we can, by analyzing a hundred observations, meet two or three among them that will agree. Sometimes agreement is manifested between members of the same family, or between persons who live together; but waiving the instances afforded by chance, by heredity, and by suggestion, it remains evident that disagreement is the general rule; and from this curious practical effects follow. Two persons having colored audition, when brought together, are not able to understand one another; each is greatly surprised at the colors which the other perceives, and we may witness, according to certain authors, some most amusing disputes. Efforts have been made to trace a mean of designations for the vowels, and to indicate the associations most frequently perceived. It is very doubtful whether such statistics can give important results, and whether the correct association can be got from the majority; for the probability must be recognized of the existence of several types of colored audition, which have not yet been clearly distinguished. Furthermore, persons are most frequently incapable of exactly determining and defining the color that appears to them. Their incapacity is associated with the facts that the shading varies not only with the words, but with the elevation of the voice that pronounces them, its timbre, and its accent, A word never has the same color from two different mouths. Consequently there is no definite red for a or for any other vowel. Some authors have nevertheless published colored diagrams in which the subjects have tried to represent their colored alphabet. These representations may hold good for colors, but not for shades; it is not that the subjects are lacking in good faith, but they can not fix with precision a color that oscillates and is transformed under the influence of a multitude of intangible causes. We can not stop with describing the phenomena, but must explain as far as we can what passes in the minds of the persons who experience impressions of color in connection with sound. What do they mean when they say, for instance, that a appears red to them?

Persons affected with colored audition form a curious illusion respecting their psychological condition. Till the moment, when they are questioned respecting their impressions, they are satisfied that the faculty of coloring sounds is natural, normal, and common to all; and they learn the contrary not without uneasiness. One is never satisfied if he knows that he possesses, deep in his mind, an exceptional trait. All of this kind that is exceptional seems abnormal, and assumes the character of a disease. This opinion is that of many doctors, who would often have much difficulty in defining the condition of psychological health, but imagine that whatever departs from that ideal and imperfectly understood condition is in the domain of pathology. Numerous authors who have written on colored audition have been laudably zealous in comforting those who perceive these impressions. Most—not all of them—have affirmed many times that it is a purely physiological act. We believe they are fundamentally right—but how far?

The phenomenon is often presented in an inexact light. It is easily understood now that it is not a disease of the eyes or the ears, but many authors continue to see in it a disorder of perception, or a double perception, or a confusion of the physiological acts of seeing and hearing.

In colored audition there is no double perception, nor what is called a synæsthesia. All takes place in the imagination of the subject; the impressions of color of which he is conscious on the hearing of certain vowels are not real sensations; they are not colors which one sees with the eyes, but mental images, notions, or we might better compare them with the images which the natural significance of the words excites in the mind. We must insist upon this important and too often misinterpreted point. In order to give a basis to our interpretation, we shall relate some of the facts we have collected with Prof. Beaunis in the Laboratory of Psychology of the Sorbonne; we shall not introduce the detail of the observations, but shall only take the general sense.

To a certain distinguished doctor a is red, and is the only vowel which appears to him in color. He has colored it spontaneously from infancy, before having read what was written on the question. The other vowels were not colored till a later age. He is suspicious of the later colorations, and believes that they are fictitious, suggested by reading. Now, what meaning shall we attribute to his expression, so clear in itself, "A is red"? Does he mean that when he sees the letter a written with a pen on a white sheet of paper, or with chalk on a black tablet, or when that vowel is pronounced in his presence, he has the subjective impression of a red spot which hovers before his eyes, on surrounding objects? In other words, is there a hallucination of sight? In no wise. Still less is there the pretended and incomprehensive seeing of the sound in red. He has the idea of red, and nothing more. It is an idea and not a sensation. According to his own expressions, he receives the same suggestion when he meets in any phrase the word red. Hear, for example, a person who is telling us of some judicial ceremony. In the midst of his story appears the phrase, "Then I saw the procurator rise in a red robe." We have immediately an internal vision of something red—a vision clear, detailed, vivid for some, confused for others. It is a like impression that the letter a gives our subject; in short, a simple idea. Let us add that the idea is not very clear; the subject can not define the shade of red that appears to him, still less represent it in real colors, even if he knows how to mix colors and is an amateur painter; it is some kind of a red—unprecise.

If we suppose, now, that all the vowels give rise to suggestions of a similar character, our description will be adapted to a majority of subjects; it will exactly represent their mental state. This mental state is characterized by the direction of the thought toward colors and shades. Each word that presents itself, whether to the eyes in reading, or to the ear in listening, or in a mental conception, gives complex ideas of color. These ideas serve as an escort to the word, accompanying it constantly, and are a scondary signification with which the word is enriched. Instead of provoking a single idea, each word provokes two—the idea of the object named, and one or several colors; likewise a phrase awakens, besides a collection of images, a series of colors. On hearing the simple words, "I am going into the country," a person with colored audition has a complex image of a trip to the country, and sees besides passing before the eyes of his imagination a succession of colors which in a subject taken at random might resolve itself into white, red, black, red, white, red, red, red, red, white.

This description may lead us to suppose that useless suggestions of color are an obstacle to the march of thought and might sometimes prevent persons from clearly comprehending the meaning of words and of reading. This case, fortunately, has not as yet presented itself; for the bands of colors do not constantly hold the first place in consciousness. When it is necessary to attend to the meaning of the words we neglect the colorations, do not remark them, and no longer perceive them. To perceive them clearly, and particularly to describe them, special attention is usually requisite, contemplation, a state of reverie, or a desire to enjoy the beautiful subjective colors, the appearance of which is usually accompanied by a vivid feeling of pleasure.

Besides the vague, undefined, and formless color-images which are most frequently provoked, the color is perceived by many persons in a form suggested by the vowel and corresponding with its outline. The language commonly used by such persons to describe their impressions does not always take note of this peculiarity. They simply say, "A is red." This means, in the present case, that when one thinks of the letter a he can not represent it otherwise than under the form of a letter painted in red. This variety of colored audition is more refined than the preceding, and also ' more complex; for it can not be found in an illiterate person, and supposes that one knows how to read. Mr. Galton has published five or six observations of this kind with figures.

Persons who have colored audition and who are cognizant of it easily recognize the nature of their subjective impressions. They i regard them as personal associations with nothing mysterious about them, and some even seek for their causes in the most commonplace and trivial circumstances. But if we cause them to describe their way of hearing, we perceive that they involuntarily attribute to these associations much more importance than they] say they do. It appears that most frequently the idea of color! suggested by a word is referred, not to the word itself, but to the! external object designated by the word. There results from this] the interesting consequence that as there are words designating some object of a red color which, on the other hand, provoke by their vowels the idea of a different color—for example, gray—the discord appears shocking, and the subjects do not hesitate to declare the word ill-formed. A doctor, a friend of ours, to whom a (French) is red, finds also that the word feu (French for fire) is incorrect, because fire is red and the word feu has no a. A correspondent to whom colored audition is a multicolored palette makes similar remarks on the contradictions or confirmations which he finds between words and their colors. To him a's are red, as to the doctor; hence he finds that red (rouge) is ill-named, and that the word fire (feu) is "that which is dullest"; scarlet (écarlate) is, on the other hand, quite imitative. I is black and o is white; whence it results that the word noir (black) is white and black; to pronounce the words moire rouge is to think of a contradiction. These plays with words, of which we might cite numerous examples, seem to us to indicate a tendency to give a real significance to associations of sound and color, as if they expressed a truth to which language ought to conform. But the subjects are too intelligent to affirm this; they simply yield to the sway of thought, without being aware of it.

There are other persons in whom the same tendency is manifested in a clearer and more simple way. They believe in good faith that certain things they have never seen have precisely the color of the word by which they are named. We have mentioned Bleuler, for example, who thought the ketones were yellow, because of the o in the name, to which he attributed that color. Observations of this kind need not be enlarged upon. For a person to believe that a thing is red because there are red vowels in its name, he must not be acquainted with its real color, and must not be aware of his faculty of coloring the vowels; for the illusion will disappear as soon as he perceives that the supposed color depends on the word. These are probably the conditions of the following observation of which I have been informed by M. Claparède. A person fifty-two years old wrote to him: "I still remember the astonishment I felt at the age of sixteen years when I saw sulphuric acid for the first time. I had previously read an account of that substance in a work of popular science, and had fancied it an opaque liquid, having the appearance of tarnished lead. I was then not yet conscious of my colored vision of the vowels. Later in life I explained my fancy as related to the two u's in the word sulphuric." This person saw i as black, and w as a lusterless metallic gray.

The same tendency, but with a very different effect, appears in a lady observed by M. Suarez de Mendoza, who attributes a special color to each piece of music and each score. The music of Haydn appears to her of a disagreeable green; that of Mozart, generally blue; Chopin's is distinguished by much yellow; Wagner's gives the feeling of an atmosphere of light, changing its colors in succession.

Having established the mental nature of the impressions of color, we come now to seek the cause of their apparition. We know pretty well what one means when he declares that a is red; but we have not explained how the idea or perception of a sound can awaken the idea of a particular color. Our ideas have generally a logical origin; we are at least in the habit of believing this, and it often occurs, in analyzing our representations, that we find the cause that brings them out and connects them. If I hear a bell, and, without seeing it, conceive its roundish form, its clapper, and its dark-green color, the connection of ideas is understood to be natural, useful, and true; it is derived from previous experiences. It is a piece of the outer world registered in my mind. But these associations of colors with sounds are factitious, have a purely individual character, and correspond with nothing in the order of external facts. A sound is a sound, and has nothing in common with a color. The human voice is grave or sharp, and is not yellow or green. How has such an association been created and developed in the face of good sense? It is evident that the act of establishing tenacious associations between impressions that have nothing in common is the sign of some intellectual form which is not everybody's. We are disposed to attach some importance to the quality of the illusions evoked. They are of a visual character, which seems to indicate that there exists in colored audition an intense rush of visual images and a tendency to think as well as to feel with them; in short, we suppose that those who have colored audition belong to the category of visuals, or persons who, according to the classification of M. Charcot and many physiologists following him, have visual memories. As the case of M. Inaudi enabled us to study a high development of the auditive memory, another category in this classification, colored audition, will perhaps permit us to study visual memory. This is only a hypothesis; for it is not absolutely certain that colored audition always agrees with the type of visual memory, and that there is a causal relation between the two things, but we do not advance it without the support of good reasons.

First, we have the testimony of the subjects whom we have had, opportunities to question. We addressing them in a tone of indifference and without trying to dictate their responses, they have' remarked that colors and forms are the things they remember most easily. A young woman to whom I sent my requests in writing to avoid the unconscious suggestions of accent, answered me, i "You ask me if I more easily recollect things seen or things] heard; things seen. When I recollect a conversation, the gestures and the attitudes of the participants recall to me what was said. Successive pictures present themselves before my eyes, and those pictures enable me to call back what I heard." That is a real visual type. In determining the type, it is necessary also to take account of the tastes of persons, their aptitudes, and their favorite occupations. Most of those whom I have seen, practice at painting or water colors, and some are painters by profession; others have been drawn by circumstances into different careers, but nearly all of them love color and Nature and have a passion for beautiful hues. Take notice also of their language. Whenever they describe their mental condition they have a marvelous abundance of picturesque expressions. Mr. Galton has justly remarked that few of those who have colored audition are satisfied with laconically naming the colors of the vowels; they must exactly define the shade, even if they are talking of white—a sensation so simple and apparently so easy to define without an epithet. They do not say, "O is white," but rather "O is a shade of white, the color of white plush, or of the under side of a fresh white mushroon." Another will say, "White mingled with milky and a little yellow"—or silver white, chalky white, etc. The use of these expressions informs, us concerning the chromatic sense of these persons. They are colorists without doubt. We who have dull imaginations have the same words at our disposal as they, but we are unable to draw the same effects out of them. Words are like the colors we use in painting. Give two identical palettes to two painters, one of whom is a colorist like Delacroix and the other a draughtsman like Ingres; with the same colors one will produce a brilliant and the other a subdued picture. What permits us to give color to the canvas, as well as in the expression of our ideas, is, above everything else, the power of mental vision.

Our hypothesis is confirmed by some facts that have been brought out in M. Claparède's investigation of "visual schemes" or such figures as Mr. Galton has found some persons associating with their groupings of numbers, and which M. Claparède has found may be associated with other abstract conceptions, like the months and the days of the week. The results of his inquiry showed a frequent coincidence of colored audition with the faculty of forming such visual schemes. Without employing visual schemes, many persons represent the figures mentally to themselves as if they were written out—a method of representation which is another good characteristic of their type of memory. I have made an experiment on this point, instructive to me, which repeated upon a number of persons has always given concordant results. I pronounce five numbers to a person and ask him to repeat them; then six, and then seven, till the number pronounced is more than the person can repeat exactly. I then ask him abruptly if he saw the numbers or heard them in his memory. Remark that this experiment appeals by its method wholly to the auditive memory. In nine cases out of ten, taking the subjects as they come, they will answer that they heard the numbers "in their ear," and had no idea of seeing them; or, if they saw them, it was by a confused, indirect mental vision. But those persons who have colored audition will answer that they saw the numbers. Although their auditive memory was excited by hearing, they transformed the auditive image of the number into a visual one; their attention was fixed on the form, the color—an excellent example of that tendency to transform everything into visions which seems to me to be the characteristic of colored audition.

This mental organization agrees in many of its characteristics, with that of the painter, the mark of whose vocation may be found, as M. Arréat has indicated in his La Psychologie du Peintre, in his sensitive-eye and his aptitude in appreciating, abstracting, and reproducing the brilliancy of colors and the harmony of forms, from which he acquires a habit of thinking with visual images. The natural gifts of the painter are, however, not all that is required for colored audition, but are only one of the psychological conditions of the phenomenon. A person capable of recollecting colors with their most delicate shadings might, by giving free course to his poetic imagination, color all the sounds that vibrate in his ear; but he would only arrive at intentional comparisons which he can make and unmake at will. The association in colored audition is very different; it is not sought for or selected; the subject does not invent it, he finds it already formed in his mind. He has only to hear a voice to have almost instantly the impression that that voice has a certain shade of color. Here we touch upon the fundamental characteristic of colored audition. Since it consists of an artificial and insurmountable association, it can not be regarded as a strictly physiological condition; it is a deviation, however insignificant we may suppose it to be, from the usual normal course of thought. Yet it generally coincides, according to the observations of the best authors, with a perfect state of physical and moral health, with perhaps a slight predominance of the nervous temperament in the majority of the subjects. The influence of heredity has been noticed several times. There have been as many as four or five cases in the same family, and considerable resemblance between the colored alphabets of relatives.

If the ultimate fundamental origin of colored audition is, as we beieve, in the organization of the individual, it remains to find the occasional cause that determines it and establishes a precise connection between each kind of sound and a color. We should not suggest the problem if we thought it impossible to solve it by some direct method, and we have a firm hope that well-conducted personal investigations will at length discover the origin of the association. It may be that some importance may be attached to the picture reading books in which the letters are colored for the pleasure of children. Possibly, too, the consonance of certain words designating colored objects has been detached, by a kind of abstraction, from the word itself, and has carried the reflection of its color to other words in which it is found, although their meaning is entirely different. This second opinion is supported by an observation cited by Mr. Galton, of a lady who gave e the color of red, and believed it was because there is an e in the English word red.

We may summarize the knowledge we have concerning the mechanism of colored audition as follows: It is certain that the impressions of color suggested by certain acoustic sensations are mental images; it is probable that those persons who experience these impressions belong to a visual type; and it is possible that the bond between the impressions is the result of associated perceptions.—Translated for The Popular Science Monthly from the Revue des Deux Mondes.