Popular Science Monthly/Volume 45/May 1894/Peculiar Sound Effects
By A. A. KNUDSON.
IN this article we propose to consider some of the peculiar features and effects of sound as we meet them in our everyday life, giving special reference to that very oft perplexing phenomenon the location of various sounds. In order that these remarks shall not extend beyond reasonable limits in our treatment of this broad subject, we shall confine them to sound effects as they originate indoors, and not so much to the origin and transmission of sounds in the atmosphere. The inability to determine at once whence a sound comes, or, as is often the case, locating it in the wrong place, occasions frequent trouble and annoyance, as we shall show by incidents in our own experience, extending over a number of years.
In order that those not familiar with the subject may obtain a fair idea of the peculiar effects of sound, as we shall herein illustrate, let us look briefly at some of its principles. In the science of acoustics, sound is simply vibrations or pulsations originating from an unlimited variety of causes, varying in amplitude, pitch, etc., passing through the intervening air, and acting upon the organs of the ear. The phonograph gives us an excellent illustration of the composition of these vibrations, for by examining with a magnifying glass the cylinder upon which the human voice has been placed either in spoken words or vocal music, we find all the vibrations which go to make up the different characteristics of sound faithfully recorded in the indentations upon the cylinder, I say faithfully recorded, because their correct reproduction is a proof of this—the result being the same also if other than vocal sounds are recorded upon the cylinder, such as music from instruments either single or combined.
If we follow the lines made by the vibrations closely, we shall see in the indentations deep and coarse punctures which represent the loud base notes of the male singer or speaker, while the fine, light, and more frequent indent represent the high notes of either a male or a female voice, and the same effect is produced by the vibrations of sounds made by musical instruments. The phonograph, therefore, enables us to capture, as it were, all manner of sounds, and to give them optical expression, while their reproduction is the wonderful feature of the whole performance.
I was once present by invitation of Mr. Edison to witness a phonograph test in his laboratory at Orange, N. J., and by way of illustrating the power of reproduction of that instrument will state the result as witnessed by me. Some fifteen or twenty phonographs were placed in a semicircle in the room, all their cylinders running, and a band of music, including a piano, stationed near the center. After the band had played a selection from some popular opera, we examined their power of reproduction by putting on the ear tubes, and, beginning at one end of the row in company with Mr. Edison, tried each phonograph.
It was found that while some reproduced the music not as loud or as clearly as desired, owing probably to imperfect adjustment, the most of them were remarkable for their loudness of sound, and so clear and perfect that the sound of each instrument such as the piano, cornet, etc., could be distinguished separately. These cylinders were taken off and, after being labeled, filed away for future use. In the phonograph Mr. Edison has given the world a most useful and valuable invention; for, beyond the fact of its commercial value, it is a most important educator in the science of acoustics, as we have attempted to point out.
Many illustrations may be found in electrical inventions where the vibrating construction of sound is taken advantage of—for instance, the musical telephones of Prof. Gray and Edison, and such ingenious inventions as the harmonic telegraph of Gray and the railway induction telegraph of Phelps and Edison. All these and many others employ the vibrating effect of sound to accomplish the desired results.
If we look for more common illustrations we may easily find them about us, such as the circuit breaker in the medical battery. By manipulating the adjusting screw, changing the number of vibrations per second, a variety of notes can be produced, from a a low rattle to a high, fine tone. The ordinary "buzzer" now common in business houses, which is largely taking the place of the electric bell, gives forth a note more or less musical according to the number of vibrations per second to which it is adjusted. The wings of the humming bird as well as those of insects furnish further examples of musical notes (not always welcome) by the rapid action of their wings against the air.
It will be observed, as this question is studied, that sound vibrations to be musical must be regular, otherwise they become simply noise. Prof. Tyndall, in his admirable work on sounds referring to this part of the subject, says that "a musical sound flows smoothly and without irregularity, and this is secured by rendering the impulses received by the tympanic membrane perfectly periodic; a periodic motion being one that repeats itself." And, again, quoting from Tyndall: "To produce a musical tone we must have a body which vibrates with the unerring regularity of a pendulum, but which can impart much sharper and quicker shocks to the air. The pulses, on the contrary, which produce noise are of irregular strength and recurrence." These illustrations will no doubt afford a fairly clear understanding of the creation and composition of sound, and we will now consider some of its effects.
One peculiar phase in sound effects is the sympathetic response of objects in the vicinity of a sound or note, such as the responding vibrations of a violin string when a note on the piano is struck with which it is in harmony.
This peculiar effect, however, is by no means confined to musical instruments, for should there be any object in a room which by accident happens to be so placed as to be in unison or tune ~with some note of a piano, that object will respond by taking up the vibrations of the note sounded. This responding note being often accompanied by a disagreeable jarring sound (due to the article touching some object while vibrating), interferes with the harmony and is often the cause of much annoyance to ladies and others who may be playing the piano; besides, these foreign sounds are so deceitful as to their location that usually they seem to come from the piano itself, and it is generally very difficult to convince a lady that they are anywhere else, and in the ladies' opinion a piano tuner must be sent for as soon as possible. An instance or two which happened in my experience will illustrate this.
The first case happened in my own home a few years ago. My wife and myself were in the parlor, she playing the piano. Presently she stopped and impatiently said, "There, this piano is not right yet, and that tuner has been here three times, and this is the note he fussed over so long" (pounding on the same), "and it's just as bad as ever." The fact was, the last time the tuner called he went away very mad, stating that he never had had such a case in all his experience. Knowing all this, the remark of my wife set me to thinking, and I asked her to pound awhile on that bad key. Upon listening carefully about the piano the jangling noise did really seem to come directly from it; but determined not to be deceived, I started on a tour of investigation, first satisfying myself that there were no loose objects upon the piano itself. I began to look about the room among bric-à-brac, mantelpiece ornaments, etc., now and then receiving such encouraging remarks from the performer as "There is no use looking away over there for that noise, it's right here in the piano; don't you hear it?" But I said, "Never mind, keep on pounding."
With the sense of hearing exercised at its best, I continued the search, but had almost given it up when, upon crossing the room and passing under the chandelier, I thought I heard the jangle above my head. Getting upon a chair, I listened carefully at each one of the glass globes, and finally came to one where I could hear the jangle quite distinctly. Upon looking at this globe carefully I discovered a very peculiar crack in it. This crack in shape was almost a complete circle, but a small stem or portion of glass at its lower edge held the piece in place, so that it was in condition to respond to the vibrations of that note of the piano with which it was in tune, and in this case it was the one that was being sounded.
The accompanying sketch will give a very fair idea of the position and shape of this piece of glass at (A). Pressing a finger against it in order to stop its vibrating, and to be quite sure that I had found the trouble, I asked the player if she heard the sound then. After several vigorous thumps she was obliged to confess that she did not. Taking away my finger and allowing it to vibrate as before, I asked again, "Do you hear it now?" The answer this time was, "Yes, it is there yet." Removing the globe, I announced the fact that the piano was fixed, much to the astonishment of the player, who found the statement correct. This incident illustrates how even the practiced ear of a musician can sometimes be deceived as to the location of sounds in music—to say nothing of the ladies, who would be excusable under such circumstances, as their sense of hearing is not expected to be so perfect as to detect such peculiar phases of sound.
Another interesting feature of peculiar sound effects is illustrated by this incident. While this loose piece of glass would respond and vibrate to one note of the piano, no other note would affect it, not even the sharp or flat of the one that caused it to respond.
If these responding objects, however, were free to vibrate without touching anything, such as a violin string, there would be no jangle, for as in the above case the edges of the broken piece of glass touched that of the globe, which caused the discordant sound, which I have termed for want of a better name the responsive jangle.
Another case similar to the above occurred in a house where I was once stopping in Nova Scotia. A piano with a bad note was fixed by simply opening an inside shutter of a bay window at the opposite side of a parlor from the piano. The latch of one shutter was lightly resting against the edge of another and caused the jangle when one particular note was struck. The lady player had previously declared that she would send for a tuner the next day, and laughed at my attempt to fix it by hunting about the room while she pounded. However, she did not conceal her surprise when the trouble was removed, and admitted that there was something about this sound business that she did not quite understand.
In regard to locating these jangles, however, I will say that it is not always so easy. It requires some practice before the ear becomes capable of locating with any degree of success the direction of sounds of this kind. This was my experience with the first piano jangle, that of the cracked globe, which was quite difficult; that of the window shutter was easier, as well as many others which I have located since. A correct musical ear is also an important adjunct in the case. I have often observed the responsive jangle in concert halls, churches, etc. One church in particular in Brooklyn that I often attended had a responsive note high up in one of the windows which I was able to locate from the pew where I sat. I formed a sort of secret attachment for this jingling note, and I looked as much for it to respond every Sunday when the organist touched the proper key as for the audience to respond to the readings of the service.
Business called me away from home and church, and after a lapse of four or five years after returning home one of the first things I looked for on again attending church was my jangle. But alas! it was gone. During my absence inside windows had been placed over all the windows in the church, and my jangling friend was silenced. No doubt the cause of this jangle was some detached piece of glass from a cracked window pane, but it was too high up to be seen.
This locating of jangles originating from musical notes having become somewhat of a hobby with me, being almost always on the lookout for them, many curious instances similar to those I have mentioned could be related, but I will give only one other, which was the first that ever came under my notice, and which took place several years ago.
This most peculiar case happened in a church on an Easter Sunday. During the singing of a hymn I at once became conscious of an occasional discordant sound quite near where I stood (the congregation were standing), and this jangle was so marked that the music for me at least had no further charms. After listening in various directions I finally located it as coming from the mouth of an elderly lady who was singing with a good deal of vim in the seat in front of me. The fact was, her false teeth were loose, some of them at least, and the effect, notwithstanding the surroundings was to me more ludicrous than inspiring. In this case it will be observed that the original sound and the jangle both came from the same place, so that it was not so difficult to locate.
There was no mistake about it, as the old lady sang through each verse, and at every verse the jangle appeared. She, however, seemed totally unconscious of any discordant effect in her vocal effort, and I have no doubt did not notice it at all.
The difficulty of locating sounds correctly may be illustrated in one way by the advantage the ventriloquist takes of this peculiarity, for in the exercise of his art he can speak in such manner that his voice appears to come from an image beside him, or from some distant place. Analogous to optical delusion, the ventriloquist might be well termed an exponent of sound delusion; and, again, the attempt to deceive an audience as to the source of sound by a supposed performer on the stage going through the motions of playing upon a cornet or other musical instrument while the real performer is behind the scenes is often successfully practiced. I was once present at a practical test made before an audience which will further illustrate how difficult it is to determine whence a sound comes. A gentleman took his seat in a chair upon the platform and was blindfolded. Another party held a snapper sounder in one hand and would produce the snap now directly over his head, now to one side, behind his back, etc. At each sound of the snapper the blindfolded party was requested to point in the direction from which he thought the sound proceeded. In almost every attempt he pointed in the wrong direction.
As a result of observations which I have made among animals, there is a wide difference between them as to the ability of distinguishing and correctly locating sound; for instance, men and women have not such an acute sense of quickly locating a sound as some of the four-footed animals, such as the rabbit, mule, the cat, and some species of dogs. It is quite probable that the ability these animals have to move their ears about, and long ears at that, accounts for the quickness they have for determining the direction of a sound. I have often tried the experiment of testing this sense of correctly locating sound with a cat by imitating the squeak of a mouse by whistling through the teeth. The first squeak or two would result in the cat springing up and, with ears erect and moving about, listen for the next sound; at the second attempt the cat would as a rule look directly into my face, as much as to say, "You can't fool me that way," would settle down again to its nap, and no further imitation squeaks would start it up again.
The not infrequent result of any unusual sound behind a mule illustrates how well his sense of hearing serves him in this respect. It is pretty well known that the mule does not wait to turn his head to see if he has correctly located the sound, but will let his heels fly first and look around afterward. The rabbit, by reason of his long ears in proportion to his size, has probably the most correct sense of locating sound of all animals.
We mortals, however, not having long ears or the ability to move those that we have, often make sad mistakes in our attempts to correctly determine the source of various sounds. In other words, the hearing facilities coupled with instinct in animals are far superior to the hearing facilities coupled even with reason in human beings.
Among human beings, however, the Indian is probably the most correct in his interpretation and location of sound, whether in ascertaining the presence of a foe or in search of game his sense of hearing in this respect through long practice attains a much higher state of perfection than that of people in various commercial or professional occupations. From my observations I should say that such animals as I have mentioned would come first on the list as the most correct locators of sound, men next, and women last. I have already shown to some extent the difficulty ladies have in this respect, and by way of illustrating further will relate an incident which occurred in Brooklyn some years ago, which will show how easily they can be mistaken should they depend upon their first impressions. Soon after the introduction of that very useful invention the pneumatic door check, designed to prevent doors from slamming, one was fixed on the entrance door of the general post office on the inside near the top. When the door closes, as every one knows, the check emits a slight hissing sound, due to the air in the cylinder escaping through a small hole. (Some later designs are without this feature.) This hiss, which is very similar to the sound often made by boys and men through their teeth in attracting attention, but considered rather insulting if applied to ladies, was the cause of a good deal of trouble one day.
A lady called at the office, and no sooner had the door closed behind her, when citt. Immediately fastening her flashing eyes upon a clerk at the stamp window, she exclaimed: "So, you are the one; I have found you at last!" and then bolted into the presence of the postmaster, where she lodged a serious complaint, viz., that she had been insulted by the aforesaid young man, and this was not his first offense, for every time she had come into the office lately "that man would go citt with his teeth." The astonished postmaster immediately sent for the accused, who heard the charge against him, but of course indignantly denied having made any such sound through his teeth, never saw the lady before, etc., etc. Finally, after the rumpus had quieted somewhat, an idea occurred to the postmaster, who was of a practical turn of mind, and he asked the lady to step out to the door a moment. Opening the door at which she entered, he let it close again, when citt, that insulting sound again. The lady was asked if that was the noise she heard, and she said, "Why, yes, that's it." Then the obliging postmaster explained to her the new door check, pointing up at the top of the door, how it worked, etc., much to the surprise and mortification of the lady, who apologized and soon left, muttering about the "new-fangled things men are always getting up."
The point I wish to make in this illustration is that the lady was completely deceived as to the location or source of this sound, and unfortunately put it in the wrong place, viz., in an innocent man's mouth several feet in front of her, when as a matter of fact it came from directly over her head. Many familiar instances of the inability of locating the source of vocal or other sounds occur every day, but I think sufficient has been said to at least put those on their guard who may read this article, should they meet with any such experiences.
In conclusion, I would suggest that the first impression of the origin or source of a sound should not be taken as absolutely correct if it is a case of importance, such as a responsive jangle produced by a musical note or accusing wrongly some innocent person, as in the case of the lady and the whistling door check. Should your piano be afflicted on one of its notes by an apparent bad sound or jangle, before sending for a tuner investigate a little on your own account while some one sounds the key.
If the trouble is due to a jangle in some part of the room, a tuner, if sent for, no doubt would "fix it," but he would in all probability tune the supposed bad string a little high or a little low, and for the time avoid the jangle in that way, collect his fee and depart, when the trouble would afterward reappear again as bad as ever. I would say further that I am not aware of any existing rules that will direct one in the correct location of sound. We can only use our ears and common sense as occasion requires, and if sometime errors are made they should not be wondered at, when the deceptive nature of the phenomena of sound is considered.
The behavior of the luminiferous ether near matter has been investigated by Prof. Oliver Lodge. The question bears upon that of whether the earth in its motion carries the ether of space with it. Prof. Lodge moved a lump of matter and ascertained whether the velocity of light in the space near it is affected by the movement. He found no such effect, and concluded that the ether slips through a solid like wind through a grove of trees; and that the connection between ether and matter is not mechanical.