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Bone conduction errors at high frequencies: implications for clinical and medico-legal practice

Published online by Cambridge University Press:  29 June 2007

Guy R. Lightfoot*
Affiliation:
Department of Clinical Engineering, Royal Liverpool University Hospital.
Jacqui B. Hughes
Affiliation:
Department of Audiology Department, Royal Liverpool University Hospital.
*
Dr Guy R. Lightfoot, Department of Clinical Engineering, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP

Abstract

The magnitude and origin of audiometric air-bone gaps in the range 3 kHz to 8 kHz was investigated in 20 normal subjects. The average gap ranged from a minimum of about 3 dB at 3 kHz to a maximum of about 19 dB at 6 kHz. Approximately 5 dB of the gap at high frequencies is caused by excess air-radiated sound from the bone vibrator. A larger error appears to result from discrepancies between the air and bone conduction standards to which audiometers are calibrated. These errors may influence diagnosis and we recommend that bone conduction tests at frequencies greater than 4 kHz are avoided. These findings have implications for medico-legal work where small air-bone gaps have diagnostic significance.

Type
Main Articles
Copyright
Copyright © JLO (1984) Limited 1993

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