THE EAR AND HEARING. 575 



faintness or loudness we may make in some cases a pretty 

 good guess. Judgments as to the direction of a sound are 

 also liable to be grossly wrong, as most persons have experi- 

 enced. However, when a sound is heard louder by the left 

 than the right ear we can recognize that its source is on the 

 left; when equally with both ears, that it is straight in front 

 or behind ; and so on. The concha has perhaps something to 

 do with enabling us to detect whether a sound originates be- 

 fore or behind the ear, since it collects, and turns with more 

 intensity into the external auditory meatus, sound-waves 

 coming from the front. By turning the head and noting 

 the accompanying changes of sensation in each ear we can 

 localize sounds better than if the head be kept motionless. 

 The large movable concha of many animals, as a rabbit or a 

 horse, which can he turned in several directions, is probably 

 an important aid to them in detecting the position of the 

 source of a sound. That the recognition of the direction of 

 sounds is not a true sensation, but a judgment, founded on 

 experience, is illustrated by the fact that we can estimate 

 much more accurately the direction of the human voice, 

 which we hear and heed most, than that of any other sound. 



