Stimulus repetition rate and the reference levels for clicks and short tone bursts: a warning to audiologists, researchers, calibration laboratories, and equipment manufacturers.

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.