Guy Lightfoot1, Yvonne Sininger, Robert Burkard, Andre Lodwig. 1. Department of Clinical Engineering, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, United Kingdom. g.lightfoot@liverpool.ac.uk
Abstract
PURPOSE: To make the audiologic community aware of a technical issue with potential for misunderstanding that could affect the design, calibration, and use of auditory brainstem response (ABR) systems. METHOD: Two international standards published in 2007 relating to the stimuli commonly used in ABR tests were studied and the behavior of a commercially available ABR system examined with regard to the relationship between stimulus level and repetition rate. RESULTS: There is potential for misunderstanding of the need to compensate for the effect of stimulus rate on stimulus level. Although rapidly presented stimuli appear louder as the rate is increased, it is inappropriate to compensate for this when calibrating the stimulus level of ABR systems. CONCLUSIONS: Users of ABR systems should, if possible, use the stimulus reference levels now available in an international standard rather than establish local values. No adjustment of level should be made to account for different stimulus repetition rates. Users of ABR systems should check their systems to ensure that no automatic level adjustment is made; if necessary, equipment manufacturers should be consulted.
PURPOSE: To make the audiologic community aware of a technical issue with potential for misunderstanding that could affect the design, calibration, and use of auditory brainstem response (ABR) systems. METHOD: Two international standards published in 2007 relating to the stimuli commonly used in ABR tests were studied and the behavior of a commercially available ABR system examined with regard to the relationship between stimulus level and repetition rate. RESULTS: There is potential for misunderstanding of the need to compensate for the effect of stimulus rate on stimulus level. Although rapidly presented stimuli appear louder as the rate is increased, it is inappropriate to compensate for this when calibrating the stimulus level of ABR systems. CONCLUSIONS: Users of ABR systems should, if possible, use the stimulus reference levels now available in an international standard rather than establish local values. No adjustment of level should be made to account for different stimulus repetition rates. Users of ABR systems should check their systems to ensure that no automatic level adjustment is made; if necessary, equipment manufacturers should be consulted.