Inaudible by certain Ears, 161 
III the natural healthy state of the human ear, there does not 
seem to be any strict limit to our power of discerning Jow sounds. 
In listening to those pulsatory vibrations of the air of which 
sound consists, if they become less and less frequent, we may 
doubt at what point tones suited to produce any musical effect 
terminate ; yet all persons but those whose organs are palpably 
defective, continue sensible of vibratory motion, until it becomes 
a mere tremor, which mav be felt and even almost counted. 
On the contrary, if we turn our attention to the opposite ex- 
tremity of the scale of audible sounds, and, with a series of pipes 
exceeding each other in sharpness, if we examine the effects of 
them successively upon the ears of any considerable number of 
persons, we shall find (even within the range of those tones 
which are produced for their musical effects) a very distinct and 
striking differetice between the powers of different individuals, 
whose organs of hearing are in other respects perfect, and shall 
have reason to infer, that human hearing in general is more con- 
fined, than has been supposed with regard to its perception of 
very acute sounds, and has probably, in every instance, some 
definite limit, at no great distance beyond the sounds ordinarily 
heard. 
It is now some years since I first had occasion to notice this 
species of partial deafness, which I at that time supposed to be 
peculiar to the individual in whom I observed it. While I Was 
endeavouring to estimate the pitch of certain sharp sounds, I 
remarked in one of my friends a total insensibility to the sound of 
a small organ pipe, which, in respect to acuteness, was far with- 
in the limits of my own hearing, as well as of others of our ac- 
quaintance. By subsequent examination, we found that his 
sense of hearing terminated at a note four octaves above the 
middle E of the piano-forte. This note he seemed to hear ra- 
ther imperfectly, but he could not hear the F next above it, al- 
though his hearing is in other respects as perfect, and his per- 
ception of musical pitch as correct as that of any ordinary ears. 
The casual observation of* this peculiarity in the organ of 
hearing, soon brought to my recollection a similar incapacity in 
a near relation of my own, whom I very well remember to have 
said, when I was a boy, that she never could hear the chirping 
VOL. IV. NOrf 7. JANUAllY 18^1. 
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