﻿of 
  tlie 
  Direction 
  of 
  Sounds. 
  309 
  

  

  plane 
  of 
  the 
  head, 
  shift 
  to 
  the 
  other 
  side 
  and 
  back 
  again 
  as 
  

   the 
  cycle 
  o£ 
  phase 
  difference 
  was 
  completed. 
  In 
  the 
  mean- 
  

   while, 
  this 
  was 
  shown 
  to 
  be 
  attainable 
  by 
  the 
  experiment 
  o£ 
  

   Lord 
  Eayleigh 
  *. 
  Later 
  Professors 
  Myers 
  and 
  Wilson 
  f, 
  

   using 
  an 
  improved 
  form 
  of 
  our 
  apparatus, 
  made 
  the 
  sound 
  

   shift 
  from 
  right 
  to 
  left 
  and 
  back 
  again 
  several 
  times, 
  as 
  the 
  

   phase 
  difference 
  was 
  steadily 
  increased, 
  and 
  they 
  plotted 
  

   curves 
  from 
  their 
  results 
  showing 
  agTcement 
  between 
  the 
  

   observed 
  and 
  theoretical 
  directions 
  based 
  on 
  this 
  idea. 
  They 
  

   also 
  advanced 
  an 
  ingenious 
  theory 
  to 
  account 
  for 
  the 
  effect 
  

   of 
  the 
  phase. 
  Our 
  knowledge 
  of 
  this 
  subject 
  has 
  recently 
  

   been 
  increased 
  by 
  other 
  investigators. 
  Mr. 
  T. 
  J. 
  Bowlker 
  J 
  

   records 
  observations, 
  in 
  which 
  he 
  found 
  this 
  influence 
  of 
  

   phase 
  difference, 
  and 
  that 
  the 
  direction 
  of 
  the 
  sound 
  shifted 
  

   over 
  to 
  the 
  opposite 
  side, 
  but 
  the 
  value 
  of 
  his 
  results 
  was 
  

   diminished 
  by 
  the 
  form 
  of 
  his 
  apparatus. 
  By 
  the 
  use 
  of 
  

   short 
  metal 
  tubes, 
  attached 
  to 
  the 
  ears 
  and 
  with 
  the 
  open 
  

   ends 
  a 
  very 
  considerable 
  distance 
  from 
  the 
  source 
  of 
  the 
  

   sound, 
  too 
  much 
  importance 
  was 
  given 
  to 
  disturbances 
  due 
  

   to 
  the 
  direct 
  transmission 
  of 
  the 
  sound 
  to 
  the 
  ears 
  and 
  to 
  the 
  

   effects 
  of 
  resonance. 
  Apparently 
  these, 
  at 
  times, 
  were 
  more 
  

   evident 
  than 
  the 
  effect 
  sought 
  for. 
  Dr. 
  Knight 
  Dunlap 
  § 
  

   has 
  brought 
  out 
  the 
  curious 
  fact 
  that 
  each 
  person 
  has 
  a 
  

   preference 
  in 
  locating 
  the 
  direction 
  of 
  a 
  sound, 
  w^hich 
  is 
  

   independent 
  of 
  the 
  position 
  of 
  the 
  source 
  and 
  which 
  varies 
  

   from 
  time 
  to 
  time 
  in 
  the 
  same 
  individual. 
  The 
  cause 
  of 
  

   this 
  preference 
  has 
  not 
  been 
  discovered. 
  In 
  the 
  same 
  

   journal 
  Mr. 
  Joseph 
  Peterson 
  || 
  has 
  a 
  monograph 
  on 
  com- 
  

   bination 
  tones 
  and 
  allied 
  problems, 
  in 
  which 
  he 
  has 
  collected 
  

   a 
  large 
  amount 
  of 
  information 
  on 
  this 
  obscure 
  subject, 
  

   and 
  he 
  has 
  added 
  a 
  critical 
  review 
  of 
  the 
  various 
  theories 
  

   extant. 
  

  

  The 
  experiments 
  in 
  this 
  paper 
  were 
  made 
  with 
  an 
  

   apparatus 
  similar 
  in 
  principle 
  to 
  that 
  in 
  my 
  former 
  work, 
  

   but 
  with 
  the 
  improvement 
  introduced 
  by 
  Myers 
  and 
  Wilson, 
  

   which 
  permits 
  of 
  a 
  continuous 
  variation 
  of 
  the 
  difference 
  of 
  

   phase 
  at 
  the 
  two 
  ears. 
  The 
  apparatus 
  (fig. 
  1, 
  p. 
  310) 
  consists 
  

   of 
  a 
  brass 
  tube, 
  260 
  cm. 
  long 
  and 
  I'D 
  cm. 
  in 
  diameter, 
  with 
  

  

  * 
  Lord 
  Ravleigli, 
  Phil. 
  Mag. 
  (G) 
  xiii. 
  p. 
  214 
  (1907). 
  

  

  t 
  Myers 
  and 
  Wilson, 
  Proc. 
  Ptoy. 
  Soc. 
  vol. 
  Ixxx. 
  p. 
  260 
  (1908). 
  See 
  

   also 
  the 
  Brit. 
  Joum. 
  Psychol., 
  yol. 
  xi. 
  p. 
  363, 
  where 
  a 
  more 
  complete 
  

   account 
  is 
  given. 
  

  

  X 
  Bowlker, 
  Phil. 
  Mag. 
  (6) 
  vol. 
  xv. 
  p. 
  318 
  (1908). 
  

  

  § 
  Dunlap, 
  Psychological 
  Eev. 
  vol. 
  x. 
  no. 
  1 
  (1909). 
  

  

  jl 
  Peterson, 
  Psychological 
  Ptev. 
  vol. 
  ix. 
  no. 
  3 
  (1908). 
  

  

  PliU. 
  ^hiy, 
  S. 
  6. 
  Yol. 
  18. 
  No. 
  104. 
  .4m/. 
  1909. 
  Y 
  

  

  