Simultaneous recording and separation of early and middle latency auditory evoked potentials

A method, consisting of wideband (1-5000 Hz) recording, dual artifact rejection (for both EEG and muscle artifacts) and separation of the EAEP by digital high-pass filtering of the averaged signal, is proposed for the simultaneous recording of early and middle latency auditory evoked potentials. The high-pass was realized by a simple recursive filter. The middle (MAEP) latency components were derivable directly from the wideband averaged signal without further filtering, thus avoiding wave form distortions. Through this method additional information on the afferent auditory system can be gained, and auditory threshold determination can be considerably improved. The proposed procedure is implementable on any computer-based EP system and does not require extra amplifiers, filters or separate test runs for the acquisition of the MAEP.