370 Mr. 11. Moon on the Structure of the Human Ear, and on 



perception of sound may occur; at the same time, that when the 

 ear is exposed to the action of condensed waves under the same 

 circumstances no motion of the fluid in the labyrinth, and con- 

 sequently no perception of sound can occur. 



The question here naturally presents itself, if, when the mem- 

 brana tympani, malleus, and incus are wanting, and the Eusta- 

 chian tube ceases to perform any recognizable function, hearing 

 occurs in a manner, in some cases, not very much less perfect 

 than when the ear is in its normal state, how comes it that a 

 machine so much more extensive and complicated is ordinarily 

 resorted to by nature for the accomplishment of that object ? 



To this it has been replied, that in the perfect ear the ma- 

 chinery is much more efficiently protected from external injury, 

 whether arising from foreign bodies which find their way into 

 the meatus, or from cold*, than is the case with the mutilated 

 organ. 



It may be added, moreover, that, on the view of the auditory 

 apparatus above set forth,, the unyielding character of the tym- 

 panal membrane must operate to protect the organ from injury 

 arising from condensations of the atmosphere, while the opposite 

 actions of the tensor muscle and of rarefactions of air must tend 

 to mitigate the effect upon the organ of the latter. 



It may readily be conceived, too, in a general way, that the ear 

 in its normal state must be a more powerful, more refined, and 

 more manageable instrument than that presented by the simple 

 labyrinth with its contents and closures, aided by the stapedius 

 muscle only. 



A more important consideration, however, still remains. 



If we regard the importance and delicacy of the functions per- 

 formed in the perfect ear by the two muscles combined and in 

 the imperfect ear by the stapedius alone, if we consider that 

 these muscles are under the influence of nerves which are not 

 involuntary but are subject to the action of the will, if we 

 advert to the very slow and gradual manner in which the recog- 

 nition of articulate sounds is developed in infancy, if we take 

 account of the apparently boundless interval between the ca- 

 pacity for appreciating sounds possessed by the obtuse rustic 

 and by the finest musical genius — if we keep in view these 

 various facts, I think it cannot but be evident that a long and 

 most delicate process of education of the nerves and muscles must 

 be passed through before that degree of proficiency is attained 

 which is requisite for the comprehension of spoken language, 

 and that one still more extended and refined must be undergone 



* The inconvenience from this latter cause, when the membrana tym- 

 pani is absent, is often verv great. See papers by Sir Astley Cooper in the 

 Philosophical Transactions" for 1800 and 1801. 



