Chirp auditory brainstem evoked response audiometry via bone conduction in normal hearing males.

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Background To determine whether patients in an audiological setting have hearing problems, normative data from similar people with normal hearing is needed. Previous research already gathered this normative data for females with LS-CE Chirps, but the male data was lacking. This data needed to be gathered with LS-CE Chirps since they are relatively new in this field. These stimuli compensate for the travelling wave delay, the upwards spread of excitation levels, and an increased change of the cochlear neural delay with frequency at lower levels. Purpose The aim of this study was gathering normative data for healthy, normal hearing adult males on Brainstem Evoked Response Audiometry (ABR) measurements, with both Air (AC) and Bone conducted (BC) stimuli. Secondly, both ABR latency data and threshold correlation data were to be examined in these normal hearing adult males. However, due to the nature of the participant group used, the data cannot be regarded as normative for the entire population. Methods The audiometric data of 20 male participants was obtained. AC and BC ABR latencies, evoked with LS-CE Chirps 1 kHz, 4 kHz and broadband, were compared with each other. ABR AC and BC hearing thresholds were compared and correlated with PTA evoked AC and BC thresholds at 1 and 4 kHz. The data of five participants from previous research were added to the analysis. Results It was found that the AC evoked latencies were shorter than the BC measurements, which is consistent with previously conducted studies. The results show that there was a significant effect (p ≤.001) of the presented frequency on the wave latencies, the broadband stimuli result in different latencies than the 1000 and 4000 Hz stimuli. Though this finding is not consistent with all previous research. Correlation measurements showed that the correlation effects between PTA and ABR thresholds varied from moderate (R = .55 for BC 4000 Hz) to strong (R=.75 for AC 4000 Hz) to very strong (R=.81 for AC 1000 Hz, R = .86 for BC 1000 Hz), though correction factors do need to be applied. However, these results should be taken with caution as the outliers in the dataset heavily influenced the significance of the correlation measurements. Conclusion The obtained data can be used in clinical practice to compare with non-healthy patients. PTA thresholds can be predicted by ABR thresholds in males when a correction factor is applied, i.e., a correction factor of 1.15 dB and a constant of 8.4 dB for 1 kHz AC, a correction factor of .95 dB for 4000 Hz AC, a correction factor of .68 dB and a constant of 5.4 dB for 1 kHz BC. The variance in PTA thresholds in 4 kHZ BC could not be predicted by ABR thresholds.
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