What the Mother of a Deaf Child Ought to Know | Page 5

months for a satisfactory color test. Color
blindness, when present, is usually most apparent in a failure to
distinguish between red and green, these two widely differing colors
seeming to produce the same impression upon the color-blind eye. The
child will be just as likely to choose a red ball to match the green one in
his hand as to select another red ball. But repeated tests should be made
before accepting color blindness as a fact, since sometimes the brain
can be educated to discriminate between red and green even when the
impressions have not the normal degree of difference.
The tests for taste, smell, muscular sense, touch, and memory cannot be
made with much thoroughness or satisfaction till two years of age,
though observation will show a recognition by taste and smell of that
which is agreeable and that which is disagreeable. Accurate tests of
hearing cannot be made till the child is three or four, but it is possible
when he is twelve months old to determine whether the hearing is
normal or is seriously impaired, and it is very desirable that this should
be done.
The expression "seriously impaired," when applied to the hearing of a
little child, must be given an entirely different interpretation than it
would have if used with reference to an adult who had previously had
normal hearing. A degree of impairment that would be unimportant in
an adult is a very serious matter in the case of a child. This is because
the ear is the natural teacher of speech and language. If the sounds of
speech are not clearly heard the imitation of them will always be
imperfect, and the acquisition of language will be impeded. If deafness
is so great that spoken words are not heard at all, then the child will not
learn to speak and to understand when spoken to unless specially taught.
A much slighter degree of deafness will prevent the proper acquisition

of speech and language than would in later life prevent the
comprehension of conversation in a familiar language. As even the
child of fifteen months would benefit from some modifications of the
ordinary treatment of a baby, if his hearing was not normally acute, it is
to his advantage to have the fact of his deafness known at once by those
in charge of him.
It is not as easy as it might seem to the inexperienced to determine even
approximately the situation of a fifteen-months-old baby with respect
to its hearing. Our interest here is, of course, in the tests of hearing that
do not require special apparatus and special training. In the case of a
child less than two years of age we must rely upon merely attracting his
attention by various sounds, judging the effect upon him by his
expression and actions. We cannot, at that age, establish a system of
responses, nor expect him to imitate the sounds he hears. Sounds
should be used for testing that disturb only the air, and are not
sufficiently low and powerful to set in vibration the floor, chair, or any
other object with which he may be in contact. Deaf children rapidly
become abnormally sensitive to vibrations, which are to them what
noises are to us. A rather smooth, not too shrill, whistle is one excellent
sound to use. Not a fluttering whistle like the postman's, nor a heavy
tone like an organ pipe or bass horn. Clapping the hands is a good
initial test of a crude nature; then a moderate whistle, varying the pitch,
for sometimes high sounds are perceived, but not low ones, or vice
versa. Then a bell, such as a small table bell, the telephone, electric
door bell, etc. Lastly, the human voice in various pitches, volumes,
distances, and vowels. Little by little it can be determined whether the
child hears all the sounds, and if not, then which, if any, he perceives.
A totally deaf child may often deceive the investigator by turning his
head at the critical moment, apparently in response to the sound that
was made, while, on the other hand, a child very slightly deaf, or not
deaf at all, may completely ignore the sounds made for the purpose of
attracting his attention. Therefore, it takes time and repeated tests under
varying environments to gradually eliminate possible errors and
coincidences.
It must be remembered that the intensity with which a sound affects the

ear varies inversely as the square of the distance from the ear to the
source of the sound. That is to say, if exactly the same sound is
repeated at half the distance, the intensity with which it reaches the ear
is four times as great as before, and if the distance is quartered, the
intensity is sixteen times as great. In