. The London, Edinburgh and Dublin philosophical magazine and journal of science . dcan be set at any desired anglewith respect to the axis of theears, and can also be turnedupon a revolving collar aboutthat axis so as to reflect sounds into the ears from any desireddirection. The theory of the Pseudophone is very simple, and is asfollows:— The intensity of a perceived sound depends upon the amountof space over which the waves are gathered by the externalcollecting apparatus of the ear; and by analogy with opticalphenomena we may say it depends upon the number of raysof sound which reach the e
. The London, Edinburgh and Dublin philosophical magazine and journal of science . dcan be set at any desired anglewith respect to the axis of theears, and can also be turnedupon a revolving collar aboutthat axis so as to reflect sounds into the ears from any desireddirection. The theory of the Pseudophone is very simple, and is asfollows:— The intensity of a perceived sound depends upon the amountof space over which the waves are gathered by the externalcollecting apparatus of the ear; and by analogy with opticalphenomena we may say it depends upon the number of raysof sound which reach the the effective surfaces of thepinnae which gather the sound-rays be /,_ and /2, and let themmake equal angles fa and fa withthe line of vision. Let the raysof sound that reach the ears fallin a direction indicated by thelines S, S, S, making an angle 6with the line of sight. The linesm and n, which are drawn per-pendicularly, measure the num-ber of sound-rays which reachthe pinnae, and are therefore pro-portional to the intensities of thesounds which reach the ears. Now. and m=/isin(0 + 0)?™=/2 sin (-#);m_/i sin (# + (/>)n /2sin(0—dy 388 Prof. S. P. Thompson on the Pseudophone. and, developing the sines, m _/\ sin 6 cos cos 6? — cos (/> sin 6?Divide by cos 6 cos $>, and reckon fl= tan 6 + tan 0. whence and But n tan m — n ~ tan 0 tan 0 = —;— tanm +72 h /I ... tan (^^—^ tan ?1 + h2 Or the difference of the intensities as compared with their sumaffords a means of comparing the angle between the line ofvision and the direction in which the sounds come, with theangle made by the effective surfaces that receive the rays ofsound*. Such an estimate as we are therefore able to make of theposition of a source of sound, judging solely by the relativeintensities of the sensation in the two ears, depends upon ourprevious perceptions and upon our possession of a constantamount of effective auditory surface, and a constant anglesubtended between the ears a
Size: 1215px × 2057px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1840, bookidlondon, booksubjectscience
