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 other words, if "ah" is spoken with a certain loudness eight inches from the child's ear, and then again with exactly the same pitch and volume only two inches from his ear, it will be sixteen times as loud to him as it was the first time. These simple tests will serve to determine whether the child has, or has not, a normal acuteness of hearing. They will not serve to determine with any accuracy the degree of impairment, if it is found that the hearing is impaired at all. More thorough tests will have to be postponed till the child is two years old or more. But the moment that impaired hearing is suspected, the best available ear specialist should be consulted in order to determine whether the cause can be removed, or measures taken to prevent a progressive increase in deafness. The visit to the otologist should be repeated at intervals of not more than eight or ten months, even where there is no question of treatment, in order that any change in the physical condition of the organs may be promptly detected. III HOW SHALL THE MOTHER GET INTO COMMUNICATION WITH HER DEAF CHILD? Let it be assumed that when the child is fifteen months old it is fairly well established that his hearing is somewhat below normal. Between fifteen months and two years of age all that is said in this section will apply equally to the child who is _feared_ to be _totally_ deaf and to one who is known to possess some sound perception, though not a normal degree of hearing. For, until he is old enough to respond to more complete and accurate tests, we must not give up the idea that he may have a sufficient remnant of hearing to be of great assistance to him in the acquisition of speech and language, if it is only developed and trained.