﻿Lord 
  Rayleigli 
  

  

  Acoustical 
  Sotei. 
  

  

  241 
  

  

  discriminate 
  front 
  and 
  back 
  when 
  the 
  voice 
  is 
  used 
  naturally. 
  

   But 
  I 
  find 
  that 
  both 
  indoors 
  and 
  outside 
  he 
  could 
  be 
  deceived. 
  

   Thus 
  when 
  standing 
  on 
  the 
  lawn 
  only 
  a 
  short 
  distance 
  in 
  

   front 
  of 
  him, 
  but 
  facing 
  from 
  him, 
  I 
  gave 
  the 
  numerals, 
  he 
  

   judged 
  that 
  I 
  was 
  behind 
  him, 
  and 
  this 
  erroneous 
  judgment 
  

   was 
  not 
  disturbed 
  even 
  when 
  I 
  conversed 
  freely 
  with 
  him. 
  

   It 
  would 
  appear 
  that 
  there 
  is 
  not 
  much 
  to 
  go 
  upon, 
  and 
  that 
  

   when 
  an 
  erroneous 
  impression 
  has 
  once 
  been 
  made 
  it 
  is 
  not 
  

   easily 
  disturbed 
  by 
  the 
  slight 
  indications 
  available. 
  Pro- 
  

   bably 
  the 
  turning 
  away 
  of 
  the 
  speaker 
  softens 
  the 
  sibilants 
  

   and 
  other 
  high 
  elements 
  in 
  the 
  sound, 
  somewhat 
  in 
  the 
  same 
  

   way 
  as 
  is 
  done 
  by 
  the 
  external 
  ears 
  of 
  the 
  listener 
  when 
  he 
  

   faces 
  away 
  from 
  the 
  sound. 
  It 
  must 
  be 
  understood 
  that 
  in 
  

   these 
  experiments 
  the 
  ears 
  were 
  used 
  in 
  a 
  natural 
  manner, 
  

   without 
  the 
  aid 
  or 
  hindrance 
  of 
  special 
  reflectors. 
  

  

  The 
  repetition 
  and 
  extension 
  of 
  these 
  observations 
  would 
  

   be 
  of 
  interest 
  ; 
  it 
  would 
  be 
  best 
  carried 
  out 
  under 
  the 
  super- 
  

   vision 
  of 
  a 
  physicist 
  young 
  enough 
  to 
  be 
  able 
  himself 
  to 
  form 
  

   judgments 
  as 
  to 
  the 
  front 
  or 
  back 
  situation 
  of 
  the 
  easier 
  

   sounds, 
  e.g. 
  of 
  the 
  voice. 
  The 
  precautions 
  necessary 
  are 
  

   indicated 
  in 
  former 
  papers. 
  

  

  The 
  Acousticon. 
  

  

  This 
  instrument, 
  intended 
  to 
  aid 
  the 
  hearing 
  of 
  the 
  partially 
  

   deaf, 
  is 
  composed 
  of 
  a 
  simple 
  battery, 
  microphone, 
  and 
  tele- 
  

   phone 
  circuit. 
  There 
  is 
  nothing 
  special 
  about 
  the 
  battery 
  

   (one 
  or 
  two 
  dry 
  cells) 
  or 
  the 
  telephone. 
  But 
  the 
  microphone 
  

   is 
  unusually 
  efficient. 
  The 
  disk 
  which 
  receives 
  the 
  sound 
  is 
  

   of 
  carbon, 
  about 
  ^ 
  mm. 
  thick, 
  and 
  is 
  clamped 
  at 
  the 
  circum- 
  

   ference. 
  Bearing 
  against 
  it 
  are 
  six 
  groups 
  of 
  small 
  (-J 
  mm.) 
  

  

  ^Cc 
  

  

  carbon 
  spheres, 
  having 
  the 
  appearance 
  of 
  shot, 
  held 
  in 
  hemi- 
  

   spherical 
  cups 
  cut 
  out 
  in 
  a 
  thick 
  plate 
  of 
  carbon 
  (figs. 
  2, 
  3). 
  

   In 
  use 
  the 
  microphone 
  may 
  be 
  worn 
  like 
  a 
  medal 
  upon 
  the 
  

  

  