416 Sounds we cannot Hear. 



is absolute. That we cannot hear them is no evidence what- 

 ever that they cannot hear one another. As a general rule, 

 the more minute animals have the more acute voices — as from 

 the laws of acoustics might be expected — and though there 

 are exceptions, as in the case of the frog ; yet the acuteness 

 of voice, and probably the range of hearing, usually bear rela- 

 tion to the size of the animal. It is therefore almost certain, 

 judging from the size alone of insects, that we should be 

 unable to hear any voices which they may possess, except 

 perhaps in case of a few of the larger of them, as the death's 

 head moth, the cicada, the grasshopper, and the cricket. 



If it be once admitted that insects and other minute 

 animals may, and probably do, utter or make determinate 

 sounds or voices, which we cannot perceive, we may readily 

 imagine them to have, like birds, sounds expressive of alarm, 

 or of encouragement, of want, or affection, of pleasure, or dis- 

 tress, and to be well enough able to communicate with one 

 another. An ant-hill or a bee-hive may be to the inhabitants 

 as noisy as a rookery appears to us ; the sound of a spider 

 may be to a fly as terrific as the roar of a lion is to an antelope ; 

 while the bat may distinguish the voice of the moths on which 

 it preys, as readily as the wolf hears the bleating of the sheep. 

 A singular converse proposition is also probable, namely, 

 that insects which can very well hear one another, do not 

 hear us at all ; that to the house-fly, or cricket, men, women, 

 and children may appear utterly dumb. Certainly many 

 insects are quite unaffected by the human voice, and, at least, 

 appear insensible to any sound from it. Even the exquisitely- 

 developed ears of the bat may be unable to hear all the notes 

 of human voices, just as the human ear often cannot hear the 

 bat's voice. 



It is stated by Scoresby and other arctic voyagers and 

 whale hunters, that whales have some mysterious mode of con- 

 verse with one another at a distance of some miles, so that an 

 alarm of danger is rapidly communicated, and this without any 

 sound audible to human beings being used. Some entirely 

 unknown mode of signaling through the medium of water has 

 been imagined to explain the fact, but it is more likely that the 

 whale simply bellows in a graver tone than ordinary — a tone 

 below the auditory range of the human ear, and therefore not 

 to be heard by it, although quite within the auditory range of 

 the whale itself. It will, of course, be understood that by 

 voice I merely mean any voluntary and determinate sound 

 given forth as a means of communication, whether the vocal 

 organs be internal, as in the higher animals ; or external, as 

 they probably are in the lower. 



