RECENT PSYCHOLOGICAL RESEARCH 229 
THE NORMAL CURVE OF ACUITY IN HEARING 
PAUL B. ANDERSON 
The speaker reported on the establishment of norms on the basis 
of records made by Mr. Bunch with the Iowa Pitch Range Audio- 
meter. The normal curve (Fig. 47) of acuity of hearing, based 
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Fig, 47 
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Prequenaj 
upon twenty-four cases of music pupils, was exhibited. In this 
figure the intensity of the sounds are on the scale of 1 to 6 as 
shown at the left, and pitches are denoted by vibration frequency 
as indicated by the numbers at the bottom. A graded series of 
norms is being established showing the norm for the best 10 per 
cent, the best 25 per cent, and .the best 50 per cent of so-called 
normal ears. Abnormalities are measured in terms of deviation 
from these norms. 
