DEBATE

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DEBATE

• In support FOR the benefit of using Real ear
  Measurement

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Over estimation of software

• A study conducted by Hawkins Cook 2003 (Hearing
  aid software predictive gain values. How
  accurate?)
• Click n fit simulation typically over predicted
  gain (by up to 10dB in the High Frequencies)
• Only way to ensure accurate verification is by in
  situ measurement

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Fig 1.
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• Kuk Ludvigson (2003) demonstrated that real ear
  measurement was essential to ensuring improved
  successful fitting
• Flexibility of modern digital aids platforms
  should prove advantageous for verification of
  fitting goals

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Average RECD ?

• Your average RECD value differs dramatically in
  paediatrics as study shown by Pasa Revit (1992)
  Individualised correction factors in pre
  selection of hearing aids
• Infant ear canal SPL values up to 20dB higher
  than measured gain output from 2cc (Michelle R.
  Petrak PHD Hearing Aid Fittings in infants
  small children)
• Variable paediatric resonant peaks for infants
  (7200Hz compared to 2700Hz in adults)
• Kreuger Reuben (1987)
• Only true accurate measurement of the ear is in
  situ

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Fig 2.

• Table of average ear volumes (Alencor et al 2005)

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Repeatability Reliability

• Repeatable real ear measurement performance of a
  digital aid within 1-5 dB
• (Ringdhal Lejon 1984, Hawkins 1987,1991)
• Accuracy of free field aided thresholds variable
  by 15dB (Hawkins et al 1987, Humes Kirn 1990)
• Measures out with normal audio frequencies (e.g.,
  a peak at 2500Hz)
• MHAS study MRC Nottingham 2000 shown REM only
  reliable source of verification

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Time Money

• Experienced REM should add no more than 5 minutes
  on to a fitting appointment
• Forth Valley Telephone review study shown 57 of
  first fits discharged without needing further
  adjustment (over 2 month study)
• Saves time and money on review appointments
• Good visual rehabilitation tool at the fitting
  appointment