HEARING, 615 
The strueture of the ampulle of the semicircular canals, 
and other parts of the labyrinth besides those specially con- 
sidered, with their peculiar hair-cells, suggests an auditory 
function; but what that may be is as yet quite undetermined. 
Fig. 458.—Distribution of cochlear nerve in spiral lamina of antero-inferior part of cochlea of 
right ear (after Sappey). 1, trunk of cochlear nerve; 2, membranous zone of spiral 
lamina ; 3, terminal expansion of cochlear nerve exposed throughout by removal of supe- 
Bor plate pf amine spiralis ; 4, orifice of communication between scala tympani and 
scala vestibuli. 
It has been thought that the parts, other than the cochlea, are 
concerned with the appreciation of noise, or perhaps the in- 
tensity of sounds; but this is a matter of pure speculation. 
AUDITORY SENSATIONS, PERCEPTIONS, AND JUDGMENTS. 
We have thus far been concerned with the conduction of 
the aérial vibrations that are the physical cause of hearing; 
but before we can claim to have “ heard” a word in the highest 
sense, certain processes, some of them physiological and some 
psychical, take place, as in the case of vision; hence we may 
speak of the affection of the end-organ or of auditory impulses, 
and of the processes by which these become, by the mediation 
of the brain, auditory sensations, and when brought under the 
cognizance of the mind as auditory perceptions and judg- 
ments. 
Auditory Judgments.—Such are much more frequently erro- 
neous than are our visual judgments, whether the direction or 
the distance of the sound be considered. As in the case of the 
eye, the muscular sense, from accommodation of the vibratory 
mechanism, may assist our judgments, being aided by our. 
stored past experiences (memory) according to the law of 
