﻿of 
  the 
  Direction 
  of 
  Sounds. 
  315 
  

  

  direction 
  requires 
  the 
  use 
  o£ 
  two 
  ears, 
  and 
  it 
  is 
  hard 
  to 
  

   determine 
  because 
  total 
  deafness 
  in 
  one 
  ear 
  alone 
  is 
  rather 
  

   rare. 
  Experiments 
  made 
  on 
  Mr. 
  Evens 
  and 
  others 
  who 
  are 
  

   hard 
  of" 
  hearing 
  in 
  one 
  ear_, 
  prove 
  that 
  they 
  locate 
  directions 
  

   about 
  as 
  readily 
  and 
  as 
  accurately 
  as 
  those 
  whose 
  hearing 
  is 
  

   quite 
  normal. 
  But 
  these 
  do 
  not 
  answer 
  the 
  question 
  as 
  the 
  

   auditory 
  nerve 
  in 
  each 
  ear 
  is 
  usually 
  unaffected, 
  the 
  trouble 
  

   being 
  with 
  the 
  drum 
  or 
  some 
  other 
  mechanical 
  defect, 
  and 
  

   sufficient 
  sound 
  reaches 
  the 
  inner 
  ear 
  to 
  produce 
  some 
  sensa- 
  

   tion. 
  I 
  was 
  fortunate 
  in 
  finding 
  a 
  person 
  whose 
  physical 
  

   ears 
  were 
  perfect 
  but 
  who 
  was 
  totally 
  deaf 
  in 
  one 
  ear, 
  and 
  

   normal 
  in 
  the 
  other, 
  in 
  fact 
  the 
  good 
  ear 
  was 
  abnormally 
  

   acute. 
  

  

  Miss 
  S., 
  after 
  an 
  attack 
  of 
  spinal 
  meningitis 
  at 
  the 
  age 
  of 
  

   four 
  years, 
  entirely 
  lost 
  the 
  sense 
  of 
  hearing 
  in 
  the 
  left 
  ear. 
  

   Examination 
  by 
  aurists 
  showed 
  that 
  the 
  nerve 
  of 
  this 
  ear 
  

   was 
  atrophied, 
  and 
  the 
  power 
  of 
  hearing 
  gone. 
  She 
  tells 
  

   me 
  that 
  she 
  experiences 
  no 
  difficulty 
  except 
  that 
  she 
  has 
  no 
  

   faculty 
  of 
  telling 
  the 
  direction 
  from 
  which 
  sounds 
  come. 
  

   On 
  hearing 
  a 
  sound 
  she 
  turns 
  her 
  head 
  indifferently 
  in 
  either 
  

   direction 
  until 
  the 
  object 
  making 
  the 
  sound 
  is 
  seen. 
  

  

  To 
  test 
  her 
  statement 
  the 
  following 
  experiments 
  were 
  

   made. 
  

  

  1. 
  The 
  ear-caps 
  were 
  applied 
  to 
  the 
  head 
  and 
  a 
  fork 
  

   sounded, 
  as 
  in 
  the 
  previous 
  experiments. 
  The 
  right 
  (good) 
  

   ear 
  was 
  stuffed 
  with 
  cotton 
  and 
  the 
  orifice 
  of 
  the 
  tube 
  into 
  

   the 
  ear-cap 
  closed 
  with 
  a 
  rubber 
  stopper. 
  The 
  tube 
  to 
  the 
  

   left 
  (deaf) 
  ear 
  remained 
  open. 
  No 
  sound 
  was 
  heard. 
  

  

  2. 
  Same 
  arrangement 
  as 
  in 
  1, 
  except 
  that 
  the 
  fork 
  was 
  

   mounted 
  on 
  a 
  resonator 
  and 
  held 
  directly 
  to 
  the 
  T-piece. 
  

   In 
  this 
  case 
  also 
  no 
  sound 
  was 
  heard. 
  

  

  The 
  intensity 
  of 
  the 
  sounds 
  used 
  in 
  these 
  and 
  in 
  the 
  

   previous 
  experiments 
  was 
  evidently 
  too 
  feeble 
  to 
  produce 
  

   sensation 
  by 
  conduction 
  through 
  the 
  head. 
  

  

  3. 
  A 
  test 
  of 
  locating 
  sounds 
  was 
  made 
  in 
  the 
  same 
  manner 
  

   as 
  described 
  earlier 
  in 
  this 
  paper. 
  In 
  all 
  positions 
  of 
  the 
  

   slider, 
  Miss 
  S. 
  merely 
  heard 
  a 
  uniform 
  tone 
  issuing 
  from 
  

   the 
  right 
  tube. 
  She 
  apparently 
  could 
  not 
  understand 
  what 
  

   I 
  meant 
  by 
  asking 
  if 
  she 
  noted 
  any 
  shift 
  or 
  change 
  in 
  the 
  

   direction 
  of 
  the 
  sound, 
  as 
  it 
  seemed 
  to 
  her 
  to 
  be 
  without 
  

   direction. 
  

  

  4. 
  Lastly, 
  a 
  test 
  was 
  made 
  to 
  see 
  if 
  she 
  could 
  determine 
  

   direction 
  without 
  the 
  use 
  of 
  the 
  apparatus. 
  She 
  was 
  seated 
  

   blindfolded 
  in 
  the 
  centre 
  of 
  a 
  room. 
  As 
  a 
  source, 
  a 
  fork 
  

   with 
  frequency 
  256 
  d. 
  v. 
  was 
  used, 
  mounted 
  on 
  its 
  resonator. 
  

   She 
  apparently 
  could 
  determine 
  direction 
  to 
  an 
  extremely 
  

  

  