The Hearing of deaf Persons more easily by Means of loud Noises, is another Argument of the Use of the Straining or Relaxation of the Tympanum in Hearing. Thus Dr. Willis (ubi supra) Accepi olim à viro fide digno, se mulierem novisse, quæ licèt surda fuerit, quousque tamen intra conclave Tympanum pulsaretur, verba quævis clarè audiebat: quare Maritus ejus Tympanistam pro servo domestico conducebat, ut illius ope, colloquia interdum cum Uxore suâ haberet. Etiam de alio Surdastro mihi narratum est, qui prope Campanile degens, quoties unà plures Campanæ resonarent, vocem, quamvis facilè audire, & non aliàs, potuit.
Abscisso Musculo [Processus majoris Mallei] in recenti aure, relaxatur [Tympani Membrana]. Valsalv. de Aur. Hum. c. 2. §. 5.
Upon considering the great Difference in Authors Opinions, about the Use of the Parts, and Manner how Hearing is performed, as also what a curious Provision there is made in the Ear, by the four little Bones, the Muscles, Membrane, &c. I was minded (since I penned this Note) to make enquiry my self into this Part, and not to rely upon Authority. And after a diligent search of various Subjects, I find we may give as rational and easie an Account of Hearing, as of Seeing, or any other Sense; as I have shewn in my last cited [Note (d) Book VII. Chap. 2.] with relation to Birds. And as to Man and Beasts, the Case is the same, but the Apparatus more complex and magnificent. For whereas in Birds, the auditory Nerve is affected by the Impressions made on the Membrane, by only the Intermediacy of the Collumella; in Man, it is done by the Intervention of the four little Bones, with the Muscles acting upon them; his Hearing being to be adjusted to all kinds of Sounds, or Impressions made upon the Membrana Tympani. Which Impressions are imparted to the auditory Nerve, in this Manner, viz. First they act upon the Membrane and Malleus, the Malleus upon the Incus, and the Incus upon the Os Orbiculare and Stapes; and the Stapes upon the auditory Nerve: For the Base of the Stapes (the same as the Operculum in Birds) not only covers the Fenestra Ovalis, within which the auditory Nerve lieth, but hath a Part of the auditory Nerve spread upon it too. It is manifest that this is the true Process of Hearing; because, if the Membrane be mov’d, you may see all the Bones move at the same Time, and work the Base of the Stapes up and down in the Fenestra Ovalis, as I shewed in this Chapter, [Note (d)] concerning the Mole; and as it may be seen in other Ears carefully opened, if the Parts remain in situ.
[w] I do not confine the Labyrinth to the Canales Semicirculares, or any other Part, as the elder Anatomists seem to have done, who by their erroneous and blind Descriptions seem not well to have understood there Parts; but with those much more curious and accurate Anatomists, Monsieur de Vernay, and Dr. Valsalva; under the Labyrinth, I comprehend the Canales Semicirculares, and the Cochlea, together with the intermediate Cavity, called by them the Vestibulum.
[x] In the semicircular Canals, two Things deserve to be noted. 1. That the three Canals are of three different Sizes, Major, Minor, and Minimus. 2. Although in different Subjects, they are frequently different; yet in the same Subject they are constantly the same. The Reason of all which, together with their Uses, Valsalva ingeniously thinks is, that as a Part of the tender auditory Nerve is lodged in these Canals, so they are of three Sizes, the better to suit all the Variety of Tones; some of the Canals suiting some, and others, other Tones. And although there be some Difference as to the Length and Size of these Canals, in different Persons; yet, lest there should be any discord in the auditory Organs of one and the same Man, those Canals are always in exact Conformity to one another in one and the same Man. V. Valsal. ubi supr. c. 3. §. 7. and c. 6. §. 4. 9.
[y] Hic posterior Nervus extra cranium delatus, in tres ramos dividitur, qui omnes motibus patheticis——inserviunt. Primus——musculis Auris impenditur. Proculdubio hujus actione efficitur, ut animalia quævis, à subito soni impulsu, aurs, quasi sonum nimis citò transeuntem captaturas erigant. Ramus alter——versus utrumque oculi angulum surculos emittit: qui musculis palpebrarum attollentibus inseruntur; quorum certè munus est ad subitum soni appulsum oculos confestim aperire, eosque velut ad Excubias vocare.——Tertius——ramus versus Linguæ radicem descendens, musculis ejus & ossis Hyoeideos distribuitur, adeóque organa quædam vocis edendæ actuat, &c. Willis’s Cereb. Anat. c. 17.
[z] Hujusmodi Nervorum conformatio in Homine usum alium insigniorem præstas, nempe ut Vox, &c. Willis Ibid.
[aa] Among the Uses to which the Wit of Man hath employ’d Sounds, we may reckon the Instruments useful in convocating Assemblies, managing Armies, and many other Occasions, wherein Bells, Trumpets, Drums, Horns, and other sounding Instruments are used; the Particularities of which it would be tedious to recount: As that the biggest Bell in Europe is reckoned to be at Erfurt in Germany, which they say may be heard twenty four Miles; with much more to the same Purpose. I shall therefore only for a Sample take notice of the Speaking-Trumpet; the Invention of which is commonly ascribed to our eminent Sir Samuel Morland; but was more probably Ath. Kircher’s; at least he had contrived such an Instrument, before Sir Samuel hit upon his. Kircher in his Phonurg. saith, the Tromba published last Year in England, he had invented twenty four Years before, and published in his Misurgia; that Jac. Albanus Ghibbesius, and Fr. Eschinardus ascribe it to him; and that G. Schottus testifieth he had such an Instrument in his Chamber in the Roman College, with which he could call to, and receive Answers from the Porter. And considering how famed Alexander the Great’s Tube was, which is said might be heard 100 Stadia, it is somewhat strange that no Body sooner hit upon the Invention. Of this Stentorophonick Horn of Alexander, there is a Figure preserved in the Vatican, which for Curiosity sake, I have from Kircher represented in [Fig. 3.] He saith its Diameter was five Cubits, and that it was suspended on a Supporter.
For the Make of the Speaking-Trumpet, and the Reason why it magnifies Sounds, I shall refer to Kircher; especially to Sir Samuel Morland’s Tuba Stentorophonica, Published in 1672.
[bb] That the Air is the Subject, or Medium of Sound, is manifest from the Experiments in rarefied and condensed Air. In an unexhausted Receiver, a small Bell may be heard at the Distance of some Paces; but when exhausted, it can scarce be heard at the nearest Distance: And if the Air be compressed, the Sound will be louder, proportionably to the Compression or Quantity of Air crouded in, as I have often tried my self, and may be seen in Mr. Hawksbee’s curious Experiments, p. 97. Also his Experiments in Phil. Trans. Nᵒ. 321.