Speech-evoked auditory brainstem response: a review of stimulation and acquisition parameters

Speech-auditory brainstem response (ABR) as a new test in the field of auditory electrophysiology, examines the auditory processing of stimuli with complex acoustic structures at the subcortical level. In recent years, speech-ABR has been administered to patients with various hearing impairments and people with special auditory skills. Results of these studies are of great interest to researchers in the fields of cognitive and auditory neurosciences. In this study, because of the increasing use of this test, a review of the studies carried out on the origin of this response and the proposed protocols to stimulate, record, and analyze this electrophysiological response are presented. The most common stimulus parameters used in the published articles was /da/ stimulus in 40 ms duration and 60-85 dB SPL intensity with the use of alternative polarity and rate of about 10 stimuli per second. The verified and widely-used acquisition parameters include using vertical electrode array with 6000 sweeps and a 30-3000 Hz filtering in a 60-70 ms time window. In determining the stimulus-record parameters of the speech-ABR test, in addition to considering the necessary minimums, the final values should always be selected based on the objectives and the study group. The unique features of this test for diagnosis and monitoring of auditory processing at supra-threshold levels, calls for comprehensive studies to formulate guidelines for the application of this test in auditory clinics but the basic points mentioned in this paper should be considered in the selection of each parameter.