Tympanum

“ When sound-waves strike the tympanum, they cause it to move inwards and outwards in a series of rapid movements. The ossicles operated by the tympanum press on the little opening O, covered by a membrane, and every time they push it in they slightly squeeze the perilymph, which in turn compresses the endolymph, which affects the nerve-ends, and telegraphs a sensation of sound to the brain. ”

“ The middle ear or tympanum (fig. 1, p) is a small cavity in the temporal bone, the shape of which may perhaps be realized by imagining a hock bottle subjected to lateral pressure in such a way that its circular section becomes triangular, the base of the triangle being above. The neck of the bottle, also laterally compressed, will represent the Eustachian tube (fig. 1, l) , which runs forward, inward and downward, to open into the naso-pharynx, and so admits air into the tympanum. ”

“ The height of the tympanum, which is in the pediment, is to be obtained thus: let the front of the corona, from the two ends of its cymatium, be measured off into nine parts, and let one of these parts be set up in the middle at the peak of the tympanum, taking care that it is perpendicular to the entablature and the neckings of the columns. The coronae over the tympanum are to be made of equal size with the coronae under it, not including the simae. Above the coronae are the simae (in Greek [Greek: epaietides] ) , which should be made one eighth higher than the height of the coronae. ”

“ But for the Free passage of the Sound into the Ear, it is requisite, that the Tympanum be tense and hard stretched; otherwise the laxness of that membrane will certainly dead and damp the Sound. And because the Tympanum is fixed in the circumference thereof to the Annulus Osseus, and so is not capable of Tension that way, in such manner as a Drum is braced; there remains another way, by drawing it at the Center into a Conoid form. And that is the principal office of the 3. Ossicles, viz, the Malleus, Incus, and Stapes ”

“ Across the end of this canal, a membrane or skin called the tympanum is stretched, like the parchment over the head of a drum, and it is this membrane which moves to and fro as the air-waves strike on it. A violent box on the ear will sometimes break this delicate membrane, or injure it, and therefore it is very wrong to hit a person violently on the ear. ”

“ There is one part of the ear still to be described, namely, the Eustachian tube, so called from Eustachius, the anatomist, who first described it. This tube opens by a wide elliptical aperture into the tympanum behind the membrane; the other end, which gradually grows wider, opens into the cavity of the mouth. By this canal the inspired air enters the tympanum to be changed and renewed, it likewise serves some important purpose in hearing, with the nature of which we are yet unacquainted. ”

“ The vibrations of the air of a room in which a musical instrument is sounded may be made manifest by the way in which fine sand arranges itself upon a thin stretched membrane over which it is strewn; and indeed Savart has thus rendered visible the vibrations of the tympanum itself. ”

“ It is believed that each is sensitive to a particular vibration rate and that each is also attached to a nerve fiber. The sound waves of the air transmitted by the tympanum, the ear bones and the liquid of the internal ear start sympathetic vibrations in the strings of the cochlea which affect the auditory nerve and we hear. The highest tones perceptible by the human ear are produced by from 24,000 to 40,000 vibrations per second. The average person cannot hear sounds produced by more than about 28,000 vibrations. ”

“ Tym′panal, Tympan′ic, like a drum: pertaining to the tympanum.—n. a bone of the ear, supporting the drum-membrane.—adj. Tym′paniform, like a tympanum.—ns. Tym′panist, one who plays a drum; Tympanī′tēs, flatulent distension of the belly.—adj. Tympanit′ic.—ns. Tympanī′tis, inflammation of the membrane of the ear; Tym′pany, any swelling, turgidity: tympanites.—Tympanic membrane, the drum-membrane of the ear ”

“ The tympanum remains as a ring within an auditory bulla; the orbit is either surrounded by bone, or separated from the hinder part of the skull by a post-orbital process of the frontal; the upper molars have broad 5-cusped crowns with a W-shaped pattern; and the intestine is generally furnished with a caecum. ”

“ No doubt it had that sense (see Cotgrave) , but not here.
Timbestere is a mere English form of the O.F. tymberesse, a player on a timbre. Diez, in his Dictionary, cites a passage from a commentary on the Psalms, given in Roquefort, Poés. franç, p. 127, to this effect:—'li tymbres est uns estrumenz de musique qui est couverz d'un cuir sec de bestes'; i. e. it is the Lat. tympanum. So also, in Wright's Vocab. col. 616, l. 28, we have:—'Timpanum, a taber, or a tymbre.' In Allit. Poems, ed. Morris, ii. 1414, we read of the sound of 'tymbres and tabornes,' and of 'symbales,' i. e. cymbals. ”

“ Hence a woman’s ordinary pitch in the lower sounds of conversation is more than an octave above a man’s; in the higher sounds it is two octaves.
And here it is important to note that by the term vibrations is meant complete ones; and by the term sonorous wave is meant a condensation and its associated rarefaction. By a vibration an excursion to and fro of the vibrating body is to be understood. Every wave generated by such a vibration bends the tympanic membrane once in and once out. These are the definitions of a vibration and of a sonorous wave employed in England and Germany. ”

“ The harmonium, accordion, concertina, etc., are reed instruments, the reed for each note being a fine strip of metal vibrating in a slit. The vocal organ of man is at the top of the windpipe, along which a continuous current of air can be forced by the lungs. Certain elastic bands are attached to the head of the windpipe, almost closing the aperture. These vocal chords are thrown into vibration by the current of air from the lungs; and as the rate of their vibration is made to vary by varying their tension, the sound changes in tone. ”

“ Does the trumpet sound? A vibration of matter causes the surrounding air to vibrate in consonance with it; and the waves of air thus created, breaking against the auditory nerve, awaken a peculiar sensation which we call sound. The trumpet, vibrating variously, as the valves are moved and the air forced through it, initiates waves of air of different lengths; and as they are communicated to the surrounding air with amazing rapidity, they successively strike the listener's ear. ”

“ 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. ”

“ 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. ”

“ In using the Audiphone during conversation there is no movement or vibration felt by the teeth; in listening to a piano there is a very faint sensation as if the Audiphone vibrated slightly, while with the handle of the Audiphone resting on the sounding-board of the piano the vibrations are so violent as to be painful to the teeth. By closing the ears a person with even acute hearing can observe the admirable manner in which the instrument conveys spoken words to the ear. ”

“ The presence of the structure is indicated by the oval disc, the drum, which is a thin tense membrane covering the auditory apparatus of nerves, ganglion cells, and auditory rods beneath.
The tympana, or drums, are not present in all Locustidæ and Gryllidæ, and, as Lubbock states, it is an additional reason for regarding them as auditory organs, that in those species which possess no stridulating organs the tympana are also wanting. In many of the Locustidæ the tympana are covered or protected by a fold of the skin projecting over them. ”

“ The ear-trumpet—which is a tube wide at one end, where the sound enters, and narrow at the other, where the ear is applied—is constructed on this principle, its sides being so curved that, according to the law of reflection, all the sound which enters it is brought to a focus in the narrow end. ”

“ 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. ”

“ If we neither leave the vocal chords apart nor bring them together quite closely, but let them touch lightly, then the air as it passes out will make them vibrate; and breath accompanied by this vibration is voice [5] in the narrower application of the word. In ordinary speech this vibration is an essential part of all vowels and of many consonants. They are accordingly called voiced [6] sounds; those produced without vibration of the vocal chords are voiceless. ”