Normative auditory brainstem response values to chirp stimulus in adults with normal hearing

Abstract

Objectives: This study aimed to establish normative values for our clinic by determining Wave V latency and amplitudes with chirpstimulus in adults with normal hearing.Patients and Methods: A total of 62 (31 males, 31 females; range, 18-60 years) individuals who had no complaints related to hearingand normal otoscopic examinations participated in the study. The participants were divided into two groups, of those age 18-39 yearsand 40-60 years. In the auditory brainstem response (ABR) recording parameters, CE-Chirp stimuli were used in repeated frequencyrarefaction polarity at the rate of 33.1/sec. For the recording window, a setting of 15 milliseconds was selected and a frequency rangeof 50-1500 Hz for the recording filter. At each level of intensity, 1500 samples were collected and averaged.Results: At 90 dB nHL, Wave I could not be obtained in 17 subjects and Wave III in 14 subjects. In Wave V values obtained from all ofthe subjects, the highest amplitude (0.41±0.12 microvolt) was determined as 70 dB nHL and the lowest latency (4.62±0.34 millisecond)90 dB nHL. In the evaluation according to gender, the Wave V latencies were more delayed in males than in females. In the age-groupevaluation, Wave V latencies were more delayed in the 40-60 years age group than in the younger age group.Conclusion: With CE-Chirp ABR over 70 dB nHL, as there was upward spread of excitation, the wave formations obtained weredistorted and amplitudes decreased. Therefore, the determination of the threshold at sound levels of 70 dB nHL and below wasconsidered appropriate for use as a diagnostic method.