View report page

The oral system, speech and lipreading, is used throughout the nursery, primary
and secondary schools. Those children with sufficient residual hearing make full use of
group hearing aid apparatus for group work in specially equipped classrooms and are
provided with individual hearing aids for personal use in and out of school.
Measurement
of hearing loss
The measurement of hearing loss began a century ago with calibrated tuning-forks
designed to lose what would now be called 1 bel after 5 seconds. By careful timing of
the period during which the fork remained audible, the amount of hearing loss could be
computed. Before the use of the audiometer was introduced into London schools, two
common methods (which are still used) of testing hearing were the watch-tick test and
the whisper test. For the watch-tick test, it was usually accepted that a normal hearing
person could hear the tick of a watch at a standard distance. Only one child was tested
at a time ; the child held his finger in one ear while the other ear was being tested. The
watch was placed at the child's ear and was slowly withdrawn until he ceased to hear it.
The same procedure was then followed in testing the other ear. The scores were averaged
to secure the child's degree of hearing. There were three difficulties : (i) the tester was
never sure that the child actually ceased to hear, or began to hear, at the instant he gave
his report ; (ii) it was doubtful that a measure of the child's ability to hear speech was
secured from the watch-tick test ; (iii) only about fifteen children could be tested in
an hour.
For the whisper test, the whisper had to be made after emptying the lungs of all
normal air and then whispering distinctly with the residual air. Only one child could be
tested at a time. The tester was twenty feet from the child, who stood with his back to
the tester. The child had to repeat what was said. If he did not do so, the tester gradually
came closer until the child did repeat the words whispered. If what was said could be
repeated at 15 feet, the score was 15-20. The test had several difficulties : (i) it was not
definitely standardised ; some testers claimed that persons of normal hearing could hear
a whisper at 30 feet ; (ii) voices differed, and this prevented satisfactory standardisation ;
(iii) only 15 children could be tested in an hour.
The ordinary methods of medical inspection failed to detect slight and early defects
of hearing and, to a considerable extent, defective hearing in one ear only.
In 1930 the Council provided a gramophone audiometer. This mechanism was a
gramophone playing a record of strings of numbers spoken at graded levels of intensity,
each usually being three decibels stronger than the next. A common range was from
30 decibels above the normal threshold down to zero. The record was played over, and
the persons being tested recorded on a form the numbers which they heard until the
numbers became inaudible. The score was then checked and the approximate decibel
loss of hearing for speech assessed.
This instrument was at first used in the London schools by an assistant aurist giving
only one half-day a week to the work. The children with hearing defects were followed
up and the great majority were found to be amenable to treatment with consequent
improvement of hearing and arrest of conditions which might have led to permanent
and progressive deafening. While useful information was obtained, it was not possible
to examine any large proportion of the children in the schools and the best use from the
instrument was not obtained. Provision was therefore made for an extended use of
gramophone audiometers for the testing of hearing of children and for their subsequent
treatment where necessary. The services of a full-time nurse and the services of an aurist
for one additional session a week were sanctioned in order that full use could be made of
the one audiometer still authorised.
The full use of the instrument began on 1st November, 1934. About 40 children
could be tested at one time and the use of the audiometer was at first confined to senior
departments. The first testing was done under the direction of the nurse, who travelled
from school to school with the apparatus ; those children failing to reach a certain
standard of hearing were given a second test. Those failing in the second test were then
192