430 SECTIONAL TRANSACTIONS.—I. 
SECTION I.—PHYSIOLOGY. 
Thursday, September 5. 
Jomnt Discussion with Section J (Psychology) on Hearing and aids to 
hearing (Section I room) (11.0). 
Dr. P. M. T. Kerripce.—The hearing of children in London schools for 
the deaf. 
About 0-1 per cent. of the school population of London are deaf enough 
to require special educational provision. ‘The deaf children vary from those 
with minor defects in hearing who only need to be taught lip-reading, to 
those who have been so severely deaf from birth that they did not acquire 
speech in the ordinary manner. The hearing of 456 children, of ages 6-17, 
in 13 schools, was tested with a pure tone audiometer. ‘Twenty per cent. were 
retested after an interval of several months, as a guide to the reliability of 
the results. 
The audiograms have been classified and compared with the clinical 
history. Cases deaf from birth had most commonly maximum hearing 
loss for high tones, or patchy hearing. Cases of deafness following infection 
of the ears had high tone maximum loss, or middle tone maximum loss, 
with about equal frequency. Meningitis usually left patchy hearing of 
small amount, or none at all. Deafness due to congenital syphilis was 
associated with audiograms similar to those of cases deaf from birth, but 
the age of onset was later. 
Speech defects have been considered in relation to the age of onset of the 
deafness, the intelligence of the child, and the amount and nature of the 
deafness. Sixty-four per cent. were deaf before the age of 2, and in these 
cases there was a definite correlation between the amount of residual hearing 
and their proficiency in speech. 
Dr. A. F. RAWDON-SMITH (11.20). 
The effect of loud pure-tone stimuli upon the acuity of hearing is discussed. 
An apparatus for producing such stimuli, and for testing the auditory 
threshold before and after their application is briefly described. It is 
shown that the absolute threshold of the ear rises as a result of pure tone 
stimulation, and that this result is not confined to the ear stimulated. A 
smaller, though often considerable, acuity loss is found in the other ear. 
This fact is thought to indicate that the losses are of cortical mediation, a 
supposition confirmed by the discovery that the losses may, on occasions, be 
restored by the application of certain unexpected stimuli. This pheno- 
menon, it is thought, places the effect in the category of inhibition, the 
unexpected stimulus producing disinhibition. These latter terms are used 
in somewhat the same sense as that employed by Pavlov, when discussing 
the inhibition of conditioned reflexes. 
The fact that a slightly greater acuity loss is found in the stimulated than 
in the unstimulated ear indicates that, in the latter, an additional peripheral 
acuity loss may be found. Such a loss has been found in the ear of the cat, 
using Davis and Saul’s method of recording the electrical activity of the 
auditory mid-brain. 
