title: Effects of click rate and electrode orientation on threshold of the auditory brainstem response.
abstract: This study evaluated the effects of stimulus presentation rate and electrode orientation on ABR threshold. Six normal-hearing adults served as subjects. ABRs were recorded from three orthogonal electrode pairs in response to click stimuli at rates of 48 and 21/s. Psychophysical thresholds were determined for each of these stimuli, and ABRs were recorded with stimuli between 0 and 10 dB SL in 2-dB steps. A ratio of ABR signal strength to noise variance (Fsp) was the criterion used to define threshold. Specifically, an Fsp value of 2.25, equivalent to a 95% response confidence using 5 and 250 degrees of freedom, was the criterion used to determine response presence within a maximum of 10,000 sweeps per average. Results revealed that, for normal-hearing adult subjects, click rate up to 48/s does not influence the sensation level at which a detectable response can be found, and a nearly vertical electrode orientation is optimal for recording the response at low levels. The predicted difference between psychophysical and ABR thresholds with a vertical electrode orientation, using 10,000 sweeps per average, up to 48 clicks per second, and an Fsp criterion of 2.25 is 4.4 dB.
authors.affiliation: Electrophysiology Lab, House Ear Institute, Los Angeles, CA 90057.
authors.forename: Y S
authors.initials: YS
authors.lastname: Sininger
authors.forename: M
authors.initials: M
authors.lastname: Don
mesh_terms: D001309:Auditory Threshold; D001933:Brain Stem; D004056:Differential Threshold; D004566:Electrodes; D005072:Evoked Potentials, Auditory; D006801:Humans; D011571:Psychoacoustics