inaudible by certain ears. 313 
hearing of different friends, as the result of various trials 
that I have made among them, I am inclined to think, that at 
the limit of hearing, the interval of a single note between two 
sounds, may be sufficient to render the higher note inaudible, 
although the lower note is heard distinctly. 
The suddenness of the transition from perfect hearing to 
total want of perception, occasions a degree of surprize, 
which renders an experiment on this subject with a series of 
small pipes among several persons rather amusing. It is 
curious to observe the change of feeling manifested by vari- 
ous individuals of the party, in succession, as the sounds ap- 
proach and pass the limits of their hearing. Those who 
enjoy a temporary triumph, are often compelled, in their 
turn, to acknowledge to how short a distance their little 
superiority extends. 
Though it has not yet occurred to me to observe a limit 
to the hearing of sharp sound in any person under so years 
of age, I am persuaded, by the account that I have received 
from others, that the youngest ears are liable to the same 
kind of insensibility. I have conversed with more than one 
person who never heard the cricket or the bat, and it ap- 
pears far more likely that such sounds were always beyond 
their powers of perception, than that they never had been 
uttered in their presence. 
The range of human hearing comprised between the 
lowest notes of the organ and the highest known cry of 
insects, includes more than nine octaves, the whole of which 
are distinctly perceptible by most ears, although the vibra- 
tions of a note at the higher extreme are six or seven hun- 
