McMurdo Sound

“ The sound was like an icy sword-blade thrust into a slumbering and tepid fountain—startling all the water spirits from repose and propriety,—or like Christmas suddenly obtruded, keen and pure, into the sluggish rest of midsummer. Of what the old man mused as his waking thoughts recognized the sound, can never be known—possibly of the wealth which he had garnered and of the broad lands over which that sound went ringing—all his own, but his own in what miserable mockery! Of what Colonel Egbert Crawford thought when the sound smote his ears, is much more certain. ”

“ He recognised that sound is propagated by waves or oscillations of the atmosphere, as light by undulations of the luminiferous ether. Water, and solid bodies, such as glass, or metal, or sonorous wood, convey the modulations with high velocity, and he conceived the plan of transmitting sound-signals, music, or speech to long distances by this means. He estimated that sound would travel 200 miles a second through solid rods, and proposed to telegraph from London to Edinburgh in this way. ”

“ The tone-waves, as they rush out of the open mouth, communicate their vibrations to the air, which conducts the sound onward until it reaches our ears, provided we are within the reach of these atmospheric vibrations. The difference between a cultivated voice or note is soon detected in the purity and regularity with which its sounds reach us as compared to the harsh, irregular, discordant waves impelled by one not so cultivated. Johannes Müller places the extreme range of the human voice at four octaves, but it is quite seldom that the range exceeds two and a half octaves. ”

“ The nature of the noise varies also very much, being either rolling, or rustling, or clanking like chains when moved, or like near thunder, as, for instance, in the city of Quito; or, lastly, clear and ringing, as if obsidian or some other vitrified masses were struck in subterranean cavities. As solid bodies are excellent conductors of sound, which is propagated in burned clay, for instance, ten or twelve times quicker than in the air, the subterranean noise may be heard at a great distance from the place where it has originated. ”

“ A strain of music or a simple tone will vibrate in the air forever and ever, decreasing according to a fixed ratio. The diffusion of the agitation extends in all directions, like the waves in a pool, but the ear is unable to detect it beyond a certain point. It is well known that some individuals can distinguish sounds which to others under precisely similar circumstances are wholly lost. Thus the fault is not in the sound itself, but in our organ of hearing, and a tone once in existence is always in existence. ”

“ The extreme highness and lowness of sounds which convey musical impression are represented, respectively, by 2,000 and by 30 vibrations per second—or by sound-waves, in the former case, of 61⁄2 inches, and in the latter, of 371⁄2 feet.
Therefore, there are not only sounds which by reason of highness or lowness are unmusical, but, beyond these, others to which the tympanum of the human ear is insensible. Nature is alive with such sounds, each carrying its three distinct properties of intensity, timbre and pitch ”

“ We know what was wrong with Ship I, and why it killed Mitch. We know—hell, we don't even begin to realize what we have at our fingertips now. It's so big it's impossible to evaluate."
"What? I don't—"
"Sound, Johnny, sound. Or rather, vibration. It's something we're just beginning to learn about. We know a few things; we know you can boil water with sound if the frequency is high enough. And you can drill metal with it—and it does things to the human body.
"There are frequencies of sound which can act directly on human nerves, directly on the human brain. ”

“ We are now prepared to realize the error of the common notion that loudness of tone is due entirely to increase of breath pressure on the vocal cords. Simple experiments with the tuning-fork have shown that while the volume of sound it gives forth is due in part to the amplitude of its vibrations, its loudness is chiefly due to the character of the resonance provided for it.
The larger the resonance chamber the greater is its reinforcing capacity. The largest air chamber in the body is the chest, which serves not only as a wind-chest, but as a resonance chamber. ”

“ 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. ”

“ Even the most important of all, the distance at which it ceases to be heard, is undecided.
“‘Up to the present time all signal-sounds have been made in air, though this medium has grave disadvantages: its own currents interfere with the sound-waves, so that a gun or bell which is heard several miles down the wind is inaudible more than a few furlongs up it. A still greater evil is that it is least effective when most needed; for fog is a powerful damper of sound.’”
Dr. ”

“ 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. ”

“ 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 to the wafting of such acoustic clouds through the atmosphere that the fluctuations in the sounds of our public clocks and of church-bells are due.
The existence of these aërial echoes has been proved both by observation and experiment. They may arise either from air-currents differently heated, or from air-currents differently saturated with vapor.
376
Rain has no sensible power to obstruct sound.
Hail has no sensible power to obstruct sound.
Snow has no sensible power to obstruct sound.
Fog has no sensible power to obstruct sound. ”

“ 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. ”

“ Merkel found that the just perceptible increment of loudness required an increase of 3/10 of the original stimulus everywhere between the intensities marked 20 and 5000 of his arbitrary scale. Below this the fractional increment of stimulus must be larger; above it, no measurements were made.
Discrimination of differences of pitch varies in different parts of the scale. In the neighborhood of 1000 vibrations per second, one fifth of a vibration more or less can make the sound sharp or flat for a good ear. ”

“ We recognize at once a difference between the sound of a vowel, say ah, sung by different persons to the same note of the piano and with the same loudness. There is a personal element, an individuality, about voices which at once arrests our attention, apart altogether from the tone or loudness. This sound-quality is determined by the form of the wave-motion, that is, by the nature of the movement of the air-particle during its little excursion to and fro in which it takes part in producing a zone of compression or rarefaction in the air and so forms a sound wave. ”

“ 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. ”

“ History records that General Washington, in his youthful days, in writing to a friend describing a battle with the Indians, said, "The sound of the bullets was music to mine ear." Now, I never had much ear for music, though I like good music, and can distinguish between good and bad music. I here and now record that the sound of shell, solid shot, grapeshot, shrapnel, minie ball, or any other kind of battle noise, was never "music to mine ear"; therefore, I conclude that any and all of these sounds, if music at all, is very poor music. ”

“ For instance, the note produced by 60 vibrations per second will chord with one produced by 120—each node of the former coinciding with each alternate node of the latter. 60 and 90 will also chord; 60 and 70 will produce discord; 60 and 65, worse discord. And so on. The science of musical composition lies in the management of sound-pulsation, and is governed by certain rigid mathematical laws—which laws the composer need not understand.
Air-movement may, of course, take place without sound-vibration, for air is only incidentally a sound-conductor. ”

“ Though the reflection of sound has the advantage of fulfilling the conditions for loudness, it introduces at the same time possibilities for setting up defective acoustics. For instance, when the walls of the room are hard and smooth very little energy is lost at each impact of the sound and many reflections take place before it finally dies out. This slow decadence of the sound, or reverberation as it is called, is the most common defect in auditoriums. ”

“ One can knock two stones together under the surface and a swimmer can hear it a mile or more away. But a horn to reproduce specific sounds is more difficult to build. It needs extra power. A sound-truck in a city, competing with all the traffic noises, will turn no more than fifteen watts of electricity into noise. But much more power would be needed to produce a similar volume under water.
Terry modified the mike into a submarine ear—an orejas de ellos. Then he began to assemble an audio amplifier to build up the volume of the sounds already taped for re-use under the sea. ”

“ It may be here noted that in a paper on experiments in audition published in 1827 Wheatstone said: “The great intensity with which sound is transmitted by solid rods at the same time that its diffusion is prevented, affords a ready means of augmenting the loudness of external sounds and of constructing an instrument which, from its rendering audible the weakest sounds, may with propriety be named the microphone.” ”

“ If one of the branches of a vibrating tuning-fork be brought near the embouchure of a flute, the lateral apertures of which are stopped so as to render it capable of producing the same sound as the fork, the feeble and scarcely audible sound of the fork will be augmented by the rich resonance of the column of air within the flute, and the tone will be full and clear. The sound will be found greatly to decrease by closing or opening another aperture ”

“ I have said nothing about the mode in which conversation is carried on below the water. Sound, as is well known, is transmitted more readily and with greater velocity through water than through air, but talking in the ordinary way is not practicable in water; for, with every word uttered, there comes out of the mouth a great bubble of air that very much interferes with the distinctness of the sound emitted, and has a most unbecoming and ridiculous appearance. ”

“ In sailing near the land every one has noticed the recoil of sounds from the shore, as voices, or the beat of a steamer's paddles. Coming through the Mussel Ridge Channel one unusually thick morning, the fog suddenly "scaled up," discovering White Head in uncomfortable proximity. The light-house keeper stood in his door, tolling the heavy fog-bell that [Pg 39] we had believed half a mile away. Our pilot gave him thanks with three blasts of the steam-whistle.
ENTRANCE TO SOME'S SOUND
Off the entrance to the Sound are several islands—Great Cranberry, of five hundred acres ”

“ The fluctuations in the strength of the sound were remarkable, sometimes sinking to inaudibility and then rising to loudness. A similar effect, due to a similar cause, is often noticed with church-bells. The acoustic transparency of the air was still further augmented on the 26th: at a distance of 9-1/4 miles from the station the whistles and horns were plainly heard against a wind with a force of 4; while on the 25th, with a favoring wind, the maximum range was only 6-1/2 miles. Plainly, therefore, something else than the wind must be influential in determining the range of the sound. ”

“ It seems evident from President Morton's statements that if the fog-signals of the maritime world, or even of one country, or even those located in the approaches to one of our great harbors, were tuned to one note, and if the ships frequenting those waters were fitted with topophones, or some similar instrument, arranged so as to be in unison with the fog-signals, that aberrations in audition, at least as to direction, might be corrected, so as to determine the location of sound to within at least one compass-point. ”