﻿318 
  Prof. 
  L. 
  T. 
  More 
  on 
  the 
  Localization 
  

  

  difEerence 
  between 
  the 
  intensities 
  at 
  the 
  two 
  internal 
  ears 
  is 
  

   not 
  large, 
  because 
  since 
  the 
  two 
  amplitudes 
  are 
  added, 
  an 
  

   imperceptible 
  amount 
  getting 
  through 
  might 
  produce 
  an 
  

   appreciable 
  difference 
  of 
  intensity/^ 
  

  

  The 
  theor}^ 
  is 
  very 
  ingenious 
  at 
  first 
  sight, 
  but 
  it 
  does 
  not 
  

   seem 
  adequate 
  when 
  considered 
  closely, 
  as 
  there 
  are 
  a 
  number 
  

   of 
  facts 
  which 
  contradict 
  it, 
  and 
  others 
  which 
  are 
  not 
  ex- 
  

   plained 
  by 
  it. 
  

  

  In 
  the 
  first 
  place, 
  the 
  head 
  always 
  casts 
  something 
  of 
  a 
  

   sound 
  shadow, 
  even 
  with 
  deep 
  tones, 
  and 
  the 
  intensity 
  at 
  the 
  

   averted 
  ear 
  is 
  always 
  a 
  little 
  less, 
  no 
  matter 
  what 
  the 
  length 
  

   of 
  the 
  sound-wave 
  may 
  be. 
  This 
  direct 
  difference 
  of 
  intensity 
  

   is 
  probably 
  as 
  great, 
  if 
  not 
  considerably 
  greater, 
  than 
  the 
  

   difference 
  of 
  intensity 
  caused 
  by 
  the 
  interference 
  of 
  the 
  

   sound 
  in 
  the 
  internal 
  ears. 
  If 
  so, 
  why 
  is 
  it 
  not 
  simpler 
  to 
  

   refer 
  localization 
  of 
  sound 
  always 
  to 
  differences 
  of 
  intensity 
  

   of 
  this 
  kind 
  at 
  the 
  outer 
  ears 
  ? 
  

  

  This 
  opinion 
  is 
  supported 
  in 
  several 
  ways. 
  In 
  my 
  experi- 
  

   ments 
  the 
  sounds 
  were 
  purposely 
  made 
  feeble, 
  so 
  feeble 
  that 
  

   sufl&cient 
  sound 
  did 
  not 
  travel 
  through 
  the 
  head 
  to 
  produce 
  

   any 
  sensation. 
  It 
  is 
  possible 
  that 
  even 
  if 
  they 
  did 
  not 
  pro- 
  

   duce 
  a 
  direct 
  sensation, 
  yet 
  they 
  might 
  cause 
  an 
  appreciable 
  

   effect 
  by 
  interference. 
  But 
  this 
  is 
  hardly 
  likely 
  when 
  we 
  

   remember 
  that 
  these 
  feeble 
  tones 
  were 
  as 
  readily 
  affected 
  in 
  

   direction 
  as 
  loud 
  ones. 
  Certainly 
  such 
  minute 
  interferences 
  

   should 
  at 
  least 
  render 
  the 
  effect 
  less 
  obvious. 
  Also 
  if 
  one 
  

   tube 
  were 
  suddenly 
  pinched, 
  so 
  as 
  largely 
  to 
  reduce 
  the 
  

   direct 
  effect 
  of 
  intensity 
  at 
  one 
  ear, 
  no 
  confusion 
  v/as 
  caused 
  

   to 
  the 
  judgement, 
  yet 
  the 
  relative 
  intensities 
  of 
  the 
  compound 
  

   tones 
  in 
  the 
  two 
  internal 
  ears 
  must 
  have 
  been 
  as 
  suddenly 
  

   and 
  as 
  greatly 
  altered, 
  and 
  this 
  should 
  by 
  their 
  theory 
  shift 
  

   the 
  direction 
  of 
  the 
  sound. 
  This 
  is 
  not 
  the 
  case. 
  An 
  ex- 
  

   periment 
  was 
  devised 
  which 
  makes 
  this 
  objection 
  very 
  forcible. 
  

   A 
  thick 
  felt 
  pad 
  was 
  inserted 
  between 
  one 
  ear-cap 
  and 
  the 
  

   head. 
  In 
  the 
  pad 
  a 
  hole 
  was 
  cut 
  the 
  size 
  of 
  the 
  opening 
  of 
  

   the 
  passage 
  into 
  the 
  ear 
  and 
  in 
  line 
  with 
  it. 
  The 
  direct 
  

   sound 
  entering 
  the 
  ear 
  was 
  thus 
  decreased 
  but 
  slightly 
  while 
  

   the 
  amount 
  of 
  sound 
  conducted 
  through 
  the 
  head 
  from 
  this 
  

   side 
  was 
  much 
  diminished^ 
  since 
  the 
  sound 
  which 
  would 
  have 
  

   struck 
  the 
  skull 
  in 
  the 
  neighbourhood 
  of 
  the 
  orifice 
  of 
  the 
  

   ear 
  was 
  stopped. 
  Now 
  if 
  the 
  pad 
  was 
  suddenly 
  removed 
  

   the 
  resultant 
  intensity 
  of 
  the 
  sound 
  in 
  the 
  opposite 
  internal 
  

   ear 
  was 
  decreased, 
  because 
  the 
  sound 
  conducted 
  through 
  the 
  

   head 
  was 
  increased 
  and 
  relatively 
  much 
  more 
  than 
  the 
  intensity 
  

   at 
  the 
  inner 
  ear 
  on 
  the 
  pad 
  side, 
  consequently 
  the 
  direction 
  

  

  