| Several studies have established that high-frequency auditory sensitivity can be estimated from BSERs to click stimuli and frequency specific stimuli with center frequencies at 2000 Hz and above, whereas the clinical utility of BSERs to frequency specific stimuli below 2000 Hz is questionable. Two classes of stimuli, constant bandwidth tone pips and constant Q (where Q is defined as frequency divided by bandwidth) third octave filtered clicks (TOFCs), systematically approximate the various combinations of frequency specific stimuli previously employed.;The present study was designed to determine whether behavioral pure tone thresholds at 500, 1000, 2000, and 4000 Hz in normal hearing subjects could be predicted better by using tone pip-evoked BSER thresholds, TOFC-evoked BSER thresholds, or a combination of the two stimuli. The test-retest reliability of the BSER threshold of the normal hearing subjects was also examined as a function of frequency and stimulus. Furthermore, preliminary data regarding the clinical utility of the two types of stimuli in two sloping and two high-frequency loss subjects were also obtained.;Findings of the present study indicate that constant Q TOFC-evoked wave D BSER thresholds estimate behavioral pure tone thresholds better than constant bandwidth tone pip-evoked wave D thresholds at 1000, 2000, and 4000 Hz in normal hearing subjects. Mean wave D BSER thresholds for 500 Hz TOFCs and 500 Hz tone pips were not significantly different. Preliminary findings in hearing impaired subjects suggest that TOFCs provide closer estimates of behavioral pure tone thresholds at 500 and 1000 Hz. At 2000 and 4000 Hz, there was no substantial difference between TOFC and tone pip thresholds in estimating behavioral pure tone thresholds.;Caution is advised in interpreting BSER thresholds, particularly in the low frequencies since BSER thresholds at 500, 1000, 2000, and 4000 Hz were as much as 63, 35, 27, and 22 dB above behavioral pure tone thresholds, respectively.;It was concluded that TOFC- and tone pip-evoked BSER audiometry should not be used as a reliable and valid means of estimating auditory sensitivity as a function of frequency at this time. |
