ABSTRACT
Objective Thresholds for auditory brain stem responses (ABRs) to tone burst and tone burst in notched noises of two different intensities were tested in adults with sensorineural hearing loss.The relationship between ABR and puretone thresholds was analyzed to identify an acoustic stimuli with better frequency-specificity.Methods Thirty-eight adults with sensorineural hearing loss (totally 45 ears) were included in the study.Tone burst used to elicit ABRs had 2.5 cycles on the rise and fall and no plateau.Notched noises of two different intensities were used to mask tone burst ipsilaterally when recording ABRs.Those two kinds of notched noises were 25 dB (intensity A) and 15 dB (intensity B) lower than tone burst in intensity respectively.Tone burst ABRs without masking were named tb-ABR,while tone burst ABRs in notched noises of intensity A and B named as amtb-ABR and bmtb-ABR.Thresholds for tb ABR,amtb ABR and bmtb-ABR were tested and analyzed.Results The regression coefficients between puretone thresholds and thresholds for tb-ABR,amtb-ABR and bmtb-ABR of all frequencies were greater than 0.8.The mean differences between ABR and puretone thresholds were all less than 10 dB.Tb-ABR thresholds the were the closest to puretone thresholds at 500 Hz,while bmtb ABR thresholds were the closest at the other three frequencies.Bmtb-ABR thresholds were more close to puretone thresholds in patients with steeply sloping hearing loss.Conclusion Thresholds for all those three ABRs could be used to predict puretone thresholds.In most condition,tb-ABR thresholds were able to estimate puretone thresholds.In some condition,different stimuli could be chosen to elicit ABR at different frequencies.It was reasonable to choose bmtb -ABR for puretone thresholds estimation in patients with steeply sloping hearing loss.
ABSTRACT
Objective To compare the accuracy of auditory brain stem response (ABR) thresholds to tone burst and tone burst ipsilaterally masked by notched noise in estimating puretone thresholds of adults with normal hearing.To study characteristics of ABRs evoked by tone burst and tone burst in notched noise of two different intensities.These three kinds of ABRs were named as follows:tb-ABR,amtb-ABR and bmtb-ABR.Methods Puretone audiometry,ABRs to tone burst and tone burst ipsilaterally masked by notched noise of different intensities were tested in 20 adults (totally 40 ears) with normal hearing.Results ①Thresholds for tb-ABR,amtb-ABR and broth-ABR of each frequency all approximated each other,and there were no statistically significant differences between them.②The mean differences between puretone thresholds and thresholds for tb-ABR,amtb -ABR and bmtb-ABR of each frequency were all less than 15 dB.Those mean differences of different ABRs of the same frequency were approximate to each other and had no statistically differences.③No matter what kind of ABR was tested,the latencies of wave V shortened with increase of frequency in each ABR at the same intensity.When the intensity and frequency of the tone burst were the same,the latency of wave V of tb-ABR was always statistically shorter than that of amtb-ABR.The latter was also always statistically shorter than that of bmtb-ABR.Conclusion Thresholds for ABRs to tone burst and tone burst ipsilaterally masked by notched noise were useful in predicting puretone thresholds.