Auditory Brainstem Responses Using Chained Stimuli of Multiple Frequency Tone Bursts

Abstract

Auditory brainstem responses (ABRs) are clinically used to evaluate the peripheral auditory system. As one of its primary clinical application, ABRs serve to estimate hearing thresholds in in difficult to test population wherein reliable behavioral thresholds cannot be obtained. The present study proposed a novel technique called Multifrequency ABR (MFABR) using which frequency specific ABRs of multiple frequencies can be obtained simultaneously. The aim of this study was to validate MFABR as a time efficient and reliable clinical tool for estimating frequency specific hearing thresholds. Thirty normal hearing adults and 11 individuals with Sensorineural hearing loss in the age range of 20 to 50years participated in the study. The latency and amplitude of wave I, III and V were compared between conventional single frequency tone burst ABR and the MFABR techniques at 500Hz, 1000Hz, 2000Hz and 4000Hz. The MFABR thresholds were also correlated with behavioral audiometric thresholds at the four aforementioned frequencies to analyze the agreement between the two types of thresholds. Results showed that MFABRs did not differ significantly from that of single frequency tone burst ABR to affect the clinical interpretations. MFABR thresholds were in close agreement with the pure tone thresholds thus validating it to be a reliable clinical tool to estimate frequency specific hearing. The total time taken for estimating thresholds across the four audiometric frequencies (500Hz, 1000Hz, 2000Hz & 4000Hz) is one-fourth of the time taken by single frequency tone bursts. Therefore it is a promising time efficient tool in diagnostic audiology, particularly in difficult to test population.