But both ears are represented in each half of
the brain; that is to say, sound vibrations entering either ear, although
they produce vibrations only in one auditory nerve, nevertheless proceed
subsequently to both auditory centres. The path most open, however, for
transmission is to the opposite hemisphere; thus the right hemisphere
receives most vibrations from the left ear and _vice versa_. Consequently
the auditory centre in the right hemisphere was able very soon to take on
the function of associating verbal sounds with the sense of movement of
articulate speech and recovery took place. _But_, when by a second attack
the corresponding vessel of the opposite half of the brain was blocked the
terminal avenues, and the central stations for the reception of the
particular modes of motion associated with sound vibration of all kinds
were destroyed _in toto_; and the patient became stone deaf. It would have
been extremely interesting to have seen whether, having lost that portion
of the brain which constitutes the primary incitation of speech, this
patient could have been taught lip language.
There is no doubt that persons who become deaf from destruction of the
peripheral sense organ late in life do not lose the power of speech, and
children who are stone deaf from ear disease and dumb in consequence can be
trained to learn to speak by watching and imitating the movements of
articulation.
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