Margaret Watts Hughes and the Shape of the Human Voice
By: Alejandro Polanco Masa
Tags: Music, Women In Tech, Inventions, Sound, History

The bases on which the eidophone was based were very simple, but it was necessary to be very observant to understand the phenomenon and to devise with it a means of registration: Someone sings in a room, while in a certain place we find a flat surface on which a handful of sand has been deposited, which comes to life by reacting by resonance to the sound, taking geometric shapes with beautiful symmetries. Sometimes these shapes will look like spirals, almost shells. In others, they will be as a leafy fern. And, from an observation like this, the eidophone was born. Margaret’s ingenuity gave, over the years, a way to record these forms created by the human voice as if they were drawings. It was not enough just to observe the phenomenon, she wanted it to become something that would be permanently preserved in physical form.

Voice figures. Image scanned from Revista Blanca, Madrid, July 1, 1903.

That device for “drawing” the human voice was truly ingenious as well as simple. With a little skill, anyone can build one and emulate the singer, in an experiment that is not only educational but also fun-filled. The eidophone consisted of a long tube, mostly made of brass or wood, with an open mouthpiece. This cylinder slightly enlarges its diameter until it ends in an elbow on which several bottomless resonance boxes were fitted, which, in their upper part, were endowed with an elastic rubber membrane that embraced its entire contour. The cups had different sizes, depending on the figure to be registered. The membranes served as a base on which were placed very fine spores of lycopodium*, whose behavior to sound seems to be much more adequate than that of sand, heavier and unpredictable. With the arrival of a sound to that kind of trumpet, the lycopodium began to dance to form certain patterns.

At the end of the 18th century the German physicist Ernst Chladni, considered one of the fathers of acoustics, had already described in great detail the geometric patterns that appear when a thin layer of sand is deposited on a flat surface and vibrated in response to certain frequencies. This illustrious predecessor of Watts Hughes as far as the visual “recording” of sound is concerned, was also one of the first to propose outer space as the place of origin of the meteorites, an idea that in his time was rejected.

Voice figures. Public Domain.

Chladni’s experiments were later popularized thanks to a description by the Irish physicist who pioneered the study of colloids, John Tyndall. At that time French mathematician Sophie Germain had also experimented with string bows and sanded surfaces for her work on vibrations. It is not known to what extent Margaret came to know these previous experiences, but concerned to improve her method of teaching singing, decided to investigate the vocalization and tones of the human voice but did not find any suitable apparatus for it. That did not stop her restlessness, designing her own contraption to register the voice. Her intention was to capture various musical notes that originated in the singing by means of a simple device. She tried different methods, membranes and, the most complicated thing, several means of registration. The sand, inherited from Chladni’s experiments, worked, but it was not very fine. Margaret experimented with all kinds of powdery, granular or even gelatinous substances until she reached what became her medium of choice: lycopodium spores. The result was wonderful because those spores, unlike other materials, did not tend to escape from the membrane, but quickly organized themselves into complex geometric patterns as they were subjected to sound. He also experimented with some success using talc.

The final procedure consisted of singing a note tuned to the end of the mouthpiece of the eidophone. The sound reached the container on which was placed the membrane in tension, which in its center contained a pile of spores of lycopodium. Shortly after being exposed to the sound, the marvelous geometric patterns of that particular musical note appeared. Naturally, if the emitter did not tune correctly or they sang the note forcibly, the result was different. As a curious fact, it is worth mentioning that if the note was maintained in time but in a decreasing form, the granules were blurring the shape created to be grouped again in the center of the membrane.

Voice figures. Image scanned from Revista Blanca, Madrid, July 1, 1903.

The process had its complexity, especially on the part of the singer object of the experiment, because the tuning had to be precise. A determined and very clean note was what was necessary to create the desired patterns. In this way, the tone, intensity, and quality of tuning could be studied in various situations. It could be said that the eidophone was a detector of tuning problems, in direct competition with the best-trained ears. A slight change of nuance, an overtone or any change in the “pure” emission of the note, and the lycopodium pattern showed variations. It was an ideal method for the study of voice and singing, but it did not go far beyond what Chladni and other later experimenters had already achieved. Where Margaret made the difference was in the systematics used and in her method for the permanent registration of images. Seeing the granules of talc or lycopodium jump on the membrane was fun, but at the end of the experiment, the figures blurred. Photography could be used to remedy it, capturing the figures in their fullness, but Mrs. Watts Hugues wanted to go further.