190 ' On Soundi inaudible by certain Ears. 



remarked in one of my friends a total insensibility to the sound 

 of a small organ pipe, which, in respect to acuteness, was far 

 within the limits of my own hearing, as well as of others of our 

 acquaintance. By subsequent examination, we found that his 

 sense of hearing terminated at a note four octaves above the mid- 

 dle E of the piano-forte. This note he seemed to hear rather 

 imperfectly, but he could not hear the F next above it, although 

 his hearing is in other respects as perfect, and his perception of 

 musical pitch as correct, as that of any ordinary ears. 



The ca^iual 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, ihat she never could hear the chirping 

 that commonly occurs in hedges during a summer's evening, 

 which I believe to be that of the grylbis campestrii. 



I have reason to think that a sister of the person last alluded 

 to had the same peculiarity of hearing, although neither of them 

 was in any degree deaf to common sounds. 



The next case which came to my knowledge was in some de- 

 gree more remarkable, in as much as the deafness in all proba- 

 bility extended a note or two lower than in the first instance. 

 This information is derived from two ladies of my acquaintance, 

 who agree that their father could never hear the chirping of the 

 common house sparrow. This is the lowest limit to acute hear- 

 ing that I have met with, and I believe it to be extremely rare. 

 Deafness even to the chirping of the house cricket, which is se- 

 veral notes higher, is not common. Inability to hear the piercing 

 squeak of the bat seems not very rare, as I have met with several 

 instances of persons not aware of such a sound. The chirping, 

 which I suppose to be that of the gnjllus campsslris, appears to 

 be rather higher than that of the bat, and accordingly will ap- 

 proach the limit of a greater number of ears ; for, as far as I am 

 yet able to estimate, human hearing in general extends but a few 

 notes above this pitch. I cannot, however, measure these sounds 

 with precision ; for it is difficult to make a pipe to sound such 

 notes, and still more difficult to appreciate the degree of their 

 acuteness. 



The chirping of the sparrow will vary somewhat in its pitch, 

 but seems to be about four octaves above E in the middle of the 

 piano-forte. 



The note of the bat may be stated at a full octave higher than ' 

 the sparrow, and 1 believe that some insects may reach as far as 

 one octave more ; for there are sounds decidedly higher than that 

 of a small pipe one-fourth of an inch in length, which cannot be 

 far from six octaves above the middle E. But since this pipe is 

 at the limit of my own hearing, I cannot judge how much the 



note 



