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Mr. C. S. Myers. The Influence of 



localise was preceded by a warning " Now " ; and the sound was allowed to 

 last for about two seconds. Immediately after each sound was given the 

 subject was required to indicate its supposed position. In the early stages 

 of practice the sounds were given at any position within the half circle 

 (from 0° to 180°) of the plane concerned, and the subject's forefinger was 

 armed with a large graduated quadrant carrying a freely movable index, so 

 that when he pointed to the apparent direction of the sound the index 

 registered the angle at which the sound appeared to be placed. In the later 

 experiments, when only three positions of the sound in any one plane were 

 employed, and the subject was either being instructed in correct localisation 

 or (still later) being tested for the effects of variations in timbre and loud- 

 ness, he learned to return his answers orally in terms of the angle from 

 which the sound appeared to come. 



Eleven subjects were investigated, seven male and four female, all under 

 40 years of age. Each sitting lasted about 40 minutes, and each subject 

 gave from three to six sittings, making from 200 to 400 judgments of 

 localisation. 



III. Experimental Results. 



1. Localisation before Practice — 



(a) For Sounds in the Median Vertical Sagittal Plane. — Without practice 

 the complex sound from the variators proved extraordinarily difficult to 

 localise. Whatever the actual position of the sound, some subjects localised 

 it in front, others localised it behind, others were unable to give any 

 consistent localisation. As one subject remarked, " I could put it anywhere ; 

 I seem to think out where it might be and then it seems to be there." 

 Another subject reported, " When you tell me where it comes from, I see it 

 can do so, and can place it there." 



When the variators were replaced by a telephone buzzer before the horn, 

 no appreciable difference in the certainty or accuracy of localisation was 

 observable. 



It was always difficult to arrange the apparatus so that the sound appeared 

 exactly in the middle line. At first the difficulty was traced to a slight leakage 

 of the sound through the flexible tube which conducted the sound from the 

 inlet pipe in the wall to the funnel-shaped opening borne on the perimeter. 

 But even when this difficulty was surmounted, the slightest error in the 

 position of the perimeter in regard to the sagittal line of the head immediately 

 occasioned lateral (right or left), instead of purely median, localisations. 



Wondering whether any possibly still remaining leakage of sound during 

 transmission could be responsible for the extreme difficulty and inaccuracy 



