Simultaneous recording of fast and slow auditory evoked potentials (slow-fast-simultaneous-ERA, SFS-ERA).

In order to reduce measurement time we have used part of the interstimulus interval of the slow cortical responses to record fast brain stem responses. For this purpose we reconstructed a programmable audiometer and preamplifier which are controlled by a computer. These, with 1/4 ms-click and tone-burst stimulation simultaneously gained fast and slow responses, not only give a frequency-related view of the threshold and the kind of hearing loss--because of amplitude and latency--, but also in some cases--because of differences between both responses--give ideas of the possible location of the hearing impairment through the auditory pathways. The audiological value of this new method is discussed and explained by giving examples of two interesting cases, one central-neural hearing loss and one questionable aggravation.