Correction of the Estimated Hearing Level of NB Chirp ABR in Normal Hearing Population

Abstract

<b><i>Introduction:</i></b> The narrowband chirp (NB Chirp), a frequency-specific sound stimulus signal obtained by limiting the frequency bandwidth based on chirp, is applied to the frequency specified auditory brainstem response (fsABR) increasingly. Although some studies demonstrated that NB Chirp-evoked auditory brainstem response (NB Chirp ABR) causes a better neural response than tone burst-evoked auditory brainstem response and is preferred for fsABR, there is little known about how to better estimate an individual’s hearing level through the threshold of NB Chirp ABR. The present study intended to compare the accuracy and deviation of NB Chirp ABR corrected by different approaches in estimating the hearing level of people with normal hearing. <b><i>Methods:</i></b> A total of 66 volunteers with normal hearing were randomly divided into a model group (<i>n</i> = 26), test group 1 (<i>n</i> = 20), and test group 2 (<i>n</i> = 20). The model group was used to calculate the threshold difference between NB Chirp ABR and pure-tone audiometry at 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz, as well as the regression equation, providing a reference for the correction of estimated hearing level of NB Chirp ABR. Test group 1 was used to observe the accuracy and deviation of the “noncorrection (N),” “threshold difference (A1),” and “regression equation (A2)” methods in correcting the estimated hearing level of NB Chirp ABR. Test group 2 was used to replicate the analysis of test group 1 to verify the repeatability of the experimental results. All data were analyzed using SPSS 24.0. <b><i>Results:</i></b> Test group 1 and test group 2 had similar results. First, the accuracy of the estimated hearing level of N was significantly higher than that of A1 or A2. Second, compared with “0,” the deviation of the estimated hearing level of N was bigger than that of A1 or A2 at 500 Hz and 1,000 Hz, while similar at 2,000 Hz and 4,000 Hz. Finally, there was no significant difference in the deviation of the estimated hearing level between A1 and A2 at 500 Hz and 1,000 Hz. <b><i>Conclusion:</i></b> Among people with normal hearing, it was necessary to correct NB Chirp ABR at 500 Hz and 1,000 Hz for lower deviation of the estimated hearing level. Both correction approaches based on threshold difference and regression equation can be used.