Soundhole

“ PITCH. The various degrees of pitch in the compass of the voice depend upon the rate of vibration of the vocal cords. This rate of vibration, the pressure of breath being the same, is caused by the different degrees of tension of the vocal cords. If the vocal cords are drawn thin and short, the pitch will be high; as the tension diminishes, the pitch will be lower. The greater the number of vibrations to the second, the higher will be the pitch. A sound consisting of sixteen vibrations to the second produces the lowest pitch that has been recognized by the human ear as sound ”

“ Chladni’s Tonometer: the Iron Fiddle, Musical Box, and the Kaleidophone
And now let us shorten our rod, so as to bring its vibrations into proper relation to our ears. When it is about four inches long, it emits a low musical sound. When further shortened, the tone is higher; and, by continuing to shorten the rod, the speed of vibration is augmented, until finally the sound becomes painfully acute. These musical vibrations differ only in rapidity from the grosser oscillations which a moment ago appealed to the eye. ”

“ Highest and Deepest Tones—Rapidity of Vibration Determined by the Siren—Determination of the Lengths of Sonorous Waves—Wave-Lengths of the Voice in Man and Woman—Transmission of Musical Sounds through Liquids and Solids
IN OUR last chapter we considered the propagation through air of a sound of momentary duration. We have to-day to consider continuous sounds, and to make ourselves in the first place acquainted with the physical distinction between noise and music. As far as sensation goes, everybody knows the difference between these two things. ”

“ When the receiver which has hitherto covered our bell is removed you hear how much more loudly it rings in the open air. When the bell was covered the aërial vibrations were first communicated to the heavy glass jar, and afterward by the jar to the air outside; a great diminution of intensity being the consequence. The action of hydrogen gas upon the voice is an illustration of the same kind. The voice is formed by urging air from the lungs through an organ called the larynx, where it is thrown into vibration by the vocal chords which thus generate sound. ”

“ Nature of sound—The ear—Musical instruments—The vibration of strings—The sounding-board and the frame of a piano—The strings—The striking mechanism—The quality of a note.
Sound differs from light, heat, and electricity in that it can be propagated through matter only. Sound-waves are matter-waves, not ether-waves. This can be proved by placing an electric bell under the bell-glass of an air-pump and exhausting all the air. Ether still remains inside the glass, but if the bell be set in motion no sound is audible. ”

“ It is also through the vibrations conveyed by the air to the little membrane called the drum of the ear that the sensations of sound are received, and of the nature of these vibrations a few words must be said presently. In considering the different qualities of sound, we have so far confined ourselves to sustained musical notes, as, for instance, the vowel sounds in singing. This has been done to show the relations of rapidity of vibration to pitch and for simplicity of illustration of the superposition of vibrations, etc. ”

“ Our churches and theatres are yet much too large, though we do not need pipes or speaking tubes. If we rub our moistened finger along the edge of a drink-big glass, or draw a bow across the strings of a violin, we can in both cases procure sounds which remain undiminished in intensity as long as the operation by which they are excited is continued. If we strike two bells, one of lead, and the other of brass, the sound of the former is feeble and momentary, compared with that of the latter ; so we see, that, though bodies all sound, yet the sounds produced are not all alike. ”

“ The action is the same on the voice of the speaker. The sounds he utters are complex and as they reach the walls certain components are reinforced and the quality of the sound is changed. This action of resonance may also be caused by the air in a room. Each room has a definite pitch to which it responds, the smaller the volume of the room the higher being the pitch. A large auditorium would respond to the very low pitch of the bass drum. ”

“ What really passes out from the source is merely a rhythmical motion of the air particles, manifesting themselves as changes in pressure, spreading out in ever-widening spheres through the atmosphere. The order of these compressions is different for every sound. The musical sounds of an orchestra embody a different set of vibrations for each note of each particular instrument. If the fluctuations in pressure of a sound wave are irregular and non-periodic, the sound is called a noise; if they are cyclic, and follow a regular and sufficiently rapid periodic lag, the sound is musical. ”

“ If there is no regular recurrence of waves, it is a noise. The rapidity of these regular beats determines the pitch of tones. That quality or timbre by which one sound is distinguished from another of the same pitch and intensity is due to the different complications of waves in the air; the ability to discriminate the various waves in the vibrating air is, therefore, the condition of our finding music in it; for every wave has its period, and what we call a noise is a complication of notes too complex for our organs or our attention to decipher. ”

“ It is known that sound is conveyed to our organs of hearing by the air: a bell struck in a vacuum emits no sound, and even when the air is thin the sound is enfeebled. Hawksbee proved this by the air-pump; De Saussure fired a pistol at the top of Mont Blanc,—I have repeated the experiment myself, and found, with him, that the sound is feebler than at the sea level. Sound is not produced by anything projected through the air. ”

“ Sound means a succession of vibrations produced in their regular order, like music, whereas noise is a disorganized vibration. For instance, falling water, like our cataract here, is sound, but the report of George's gun was a noise."
"I can see the difference. Would a wagon going rapidly over a pavement be a noise or a sound?" ”

“ Noise affects us as an irregular succession of shocks. We are conscious while listening to it of a jolting and jarring of the auditory nerve, while a musical sound flows smoothly and without asperity or irregularity. How is this smoothness secured? By rendering the impulses received by the tympanic membrane perfectly periodic. A periodic motion is one that repeats itself. The motion of a common pendulum, for example, is periodic, but its vibrations are far too sluggish to excite sonorous waves. ”

“ If the Sonorous Body be plac'd near Water, the Sound will easily be convey'd, yet mollified; as Experience teacheth us from a Ring of Bells near a River, and a great Gun shot off at Sea, which yet differ much in the strength, and softness and continuance, or propagation of their Sounds, from the same at Land, where the Sound is more harsh and more perishing, or much sooner decays.
3. In a Plain a Voice may be heard at a far greater distance than in uneven Ground. ”

“ Near sounds are louder than distant ones. Now, by preserving the same pitch, quality, and duration, but with an accurately graduated reduction of loudness, a series forming a perspective of sounds may be created, which, falling in succession on the ear, will suggest to the mind a constantly increasing distance of the sound’s source. ”

“ After listening for a few moments, a distant, unearthly noise becomes faintly audible—a long, low, mysterious moaning, which never changes, which is felt on the ear as well as heard by it—a sound that might proceed from some incalculable distance, from some far invisible height—a sound so unlike anything that is heard on the upper ground, in the free air of heaven ”

“ On the approach of a railway train the pitch of the whistle is higher, on the retreat of the train the pitch is lower, than it would be if the train were at rest.
Musical sounds are transmitted by liquids and solids. Such sounds may be transferred from one room to another; from the ground-floor to the garret of a house of many stories, for example, the sound being unheard in the rooms intervening between both, and rendered audible only when the vibrations are communicated to a suitable sound-board. ”

“ It is certain, however, that it is one of the commonest of sound producers; if there is a boy in the home there is almost sure to be a whistle in the house. Few trouble about the scientific explanation of the sound produced by this common instrument, but experts tell us that the sound comes because condensations occur by the collision of air against the cutting edge placed in its path. ”

“ The loudness of sound is such as is convenient for common purposes. The organs of speech can, in the present constitution of the air, produce, without fatigue, such a tone of voice as can be heard with distinctness and with comfort. That any great alteration in this element might be incommodious, we may judge from the difficulties to which persons are subject who are dull of hearing, and from the disagreeable effects of a voice much louder than usual, or so low as to be indistinct. Sounds produced by the human organs, with other kinds of air, are very different from those in our common air. ”

“ The wind always howled around the lamasery, up so high. From what we knew about acoustics and how they shaped the old phonograph horns to increase sound amplification, we worked it out that we were in a sort of wind-tunnel or horn, and it didn’t seem that they opened any rock at the image or we would have heard it. If the far end of the tunnel opened, and wind howled in and through the hollow image, it could make those weird howls, high and low, moans and screeches. So we followed the tunnel down, and by using Tip’s pencil flashlight we located a lever, and risked making the sound. ”

“ In wires and bells the bodies themselves produce the sounds we hear. In wind instruments and the voice the air is the cause of the sound.
The very deepest notes are produced by the fewest vibrations. Fourteen or fifteen vibrations will give us a very low note, if not the very lowest. The pipe of sixteen feet, closed at its upper end, will produce sound waves of thirty-two feet. High notes can be formed from vibrations up to 48,000 in a second. Beyond these limits the ear cannot accept a musical sound. ”

“ All voice-sounds are made by two elastic bands or cushions, called vocal chords, stretched across the end of the tube or windpipe through which we breathe, and as we send the air through them we tighten or loosen them as we will, and so make them vibrate quickly or slowly and make sound-waves of different lengths. But if you will try some day in the woods you will find that a bird can beat you over and over again in the length of his note ”

“ A sound-wave certainly bends thus round an obstacle, though as it diffuses itself in the air at the back of the obstacle it is enfeebled in power, the obstacle thus producing a partial shadow of the sound. A railway train passing through cuttings and long embankments exhibits great variations in the intensity of the sound. ”

“ Far different is it with the longer waves of sound. If the window is open, we are able to hear practically all the sounds from outdoors, even that of a wagon around the corner, although we may be at the other end of the room away from the window. The longer sound waves spread out and bend at right angles around corners, so that it is almost impossible to get a sound shadow with them. Furthermore, in the matter of reflection, it appears that the area of the reflecting wall must be comparable with the length of the waves being reflected. ”

“ A simple noise being a sound-wave, has its wave-form or make-mark. The blending of many such would produce a tone in that likeness; hence, a musical note is a blending of like noises, and every noise is really the first wave, the key-note of a musical tone. Take the ringing of a door-bell. Here the ear hears not only a musical tone, a sound-blend, in the ring of the bell, but also the noise of the clapper's clang, clang, clang. The vibrations of the bell throw the air into musical waves, shown in Fig. 5, while a huge clang-wave will sweep
Fig. ”

“ But the tremendous currents above us, which sweep along the vast masses of vapor, are noiseless until they touch the earth, and some little trifling eddies are made in their lower sweep by hills and trees and houses. It is then only noise. The ear requires yet smaller waves of air to experience the sensation of tone. The lowest note of a piano has barely enough of it to give a definite idea. As the waves become shorter, the ear begins to be pleasantly affected, and the realm of music is reached. ”

“ The general terms—loudness and quality, embrace all the distinctions heard in a noise, as in the collision of two unelastic sticks. Pitch and duration can scarcely be considered as belonging to common noise. Thus we have— (1) noise whose audible distinctions are comprehended under the general terms loudness and quality; (2) common sound, whose audible distinctions are comprehended under the general terms—loudness, quality, duration, and every varying pitch; (3) musical sound, whose audible distinctions are comprehended under the general terms—loudness, quality, duration, and uniform pitch. ”