﻿Audibility 
  Factor 
  of 
  a 
  Shunted 
  Telephone. 
  133 
  

  

  Bo/S. 
  

  

  Eo+S 
  

  

  Z+S 
  

  

  I 
  (total) 
  

  

  lo, 
  B 
  °+ 
  S 
  

  

  log 
  !. 
  

   8 
  Ir 
  

  

  S 
  

  

  S 
  

  

  I 
  (receiver) 
  

  

  0-25 
  

  

  1-25 
  

  

  2 
  

  

  1-85 
  

  

  0-097 
  

  

  0-267 
  

  

  0-5 
  

  

  IS 
  

  

  3 
  

  

  2-8 
  

  

  0176 
  

  

  447 
  

  

  1 
  

  

  2 
  

  

  5 
  

  

  4-77 
  

  

  0-301 
  

  

  0-679 
  

  

  3 
  

  

  4 
  

  

  13 
  

  

  12-72 
  

  

  0-602 
  

  

  1-104 
  

  

  10 
  

  

  11 
  

  

  41 
  

  

  40-71 
  

  

  1-041 
  

  

  1-61 
  

  

  30 
  

  

  31 
  

  

  121 
  

  

  120-7 
  

  

  1-491 
  

  

  2-081 
  

  

  100 
  

  

  101 
  

  

  401 
  

  

  400-7 
  

  

  2-004 
  

  

  2-602 
  

  

  In 
  view 
  of 
  the 
  unavoidable 
  lack 
  of 
  precision 
  in 
  all 
  audi- 
  

   bility 
  tests 
  it 
  is 
  obviously 
  sufficiently 
  accurate 
  to 
  neglect 
  the 
  

  

  phase 
  of 
  the 
  telephone 
  current 
  and 
  take 
  — 
  ^ 
  — 
  as 
  the 
  

   audibility 
  factor. 
  

  

  The 
  figure 
  is 
  a 
  reproduction 
  of 
  fig. 
  2 
  in 
  Mr. 
  van 
  der 
  Pol's 
  

   paper, 
  with 
  the 
  addition 
  of 
  two 
  dotted 
  lines 
  which 
  represent 
  

  

  T 
  T? 
  -I- 
  S 
  

  

  log 
  M 
  plotted 
  against 
  log 
  y- 
  instead 
  of 
  log 
  — 
  ^ 
  — 
  . 
  For 
  the 
  

  

  upper 
  dotted 
  line 
  it 
  has 
  been 
  assumed 
  that 
  Z 
  = 
  3E 
  , 
  whilst 
  for 
  

  

  2-6 
  

   2-4 
  

   2-2 
  

   20 
  

   1-8 
  

   1-6 
  

   1-4 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  logM 
  

  

  

  

  

  

  

  

  

  

  

  

  **■ 
  

  

  ■<" 
  

  

  

  

  

  

  

  

  

  ^ 
  

  

  

  X-: 
  

  

  4 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  < 
  

  

  [*<\ 
  

  

  '<**■> 
  

  

  * 
  

  

  

  

  

  

  

  

  

  ^> 
  

  

  «£ 
  

  

  ^ 
  

  

  #2 
  

  

  * 
  

  

  

  

  

  

  

  

  

  

  ** 
  

  

  '/- 
  

  

  

  

  

  

  

  l°g- 
  

  

  Ktota 
  

  

  1) 
  

  

  

  

  Krecejver) 
  

  

  0-2 
  0-4 
  0-6 
  0-8 
  1-0 
  

  

  1-4 
  1-6 
  1-8 
  2-0 
  22 
  2-4 
  2-6 
  

  

  the 
  lower 
  Z 
  = 
  4R 
  as 
  in 
  the 
  table 
  above. 
  It 
  is 
  seen 
  that 
  if 
  the 
  

   impedance 
  of 
  the 
  receivers 
  is 
  three 
  or 
  four 
  times 
  their 
  con- 
  

   tinuous 
  current 
  resistance, 
  the 
  resultant 
  curve 
  is 
  considerably 
  

   modified, 
  and 
  with 
  it 
  the 
  conclusions 
  based 
  thereon. 
  If 
  

   further 
  tests 
  show 
  that 
  the 
  results 
  are 
  not 
  modified 
  when 
  the 
  

   resistance 
  of 
  the 
  detector 
  circuit 
  is 
  kept 
  constant, 
  it 
  would 
  

   appear 
  from 
  the 
  slope 
  of 
  the 
  dotted 
  lines 
  that 
  the 
  audibility 
  

   factor 
  varies 
  as 
  a 
  higher 
  power 
  than 
  the 
  square 
  of 
  the 
  radio- 
  

   frequency 
  current. 
  This 
  appears 
  improbable. 
  

  

  