< Program

Technology Update Session

Session 1B
Advances in SmartEP - Simultaneous Acquisition of Frequency Following Responses and Cortical Evoked Potentials
Rafael E. Delgado, PhD, Intelligent Hearing Systems Corp

Currently, the auditory neural pathways are evaluated in a fragmented approach using different protocols and recording sessions. This is due to several factors: Current commercial systems typically record data using small data buffers (e.g., 1024 data points). Due to the frequency composition and duration of the various neural responses, the higher sampling rate required to acquire subcortical responses does not allow recording CAEPs in the same acquisition buffer. Similarly, the low sampling rate used to record CAEP responses is not sufficiently high for subcortical responses and requires different high and low pass filters. In addition, the response amplitudes and signal-to-noise (SNR) characteristics differ greatly from early (small amplitude requiring more averaging) to late potentials (large amplitude requiring fewer averages). A new acquisition method developed to acquire simultaneous Early and Late Latency Responses (simE-LLR), will be presented. The recording of subcortical frequency following responses (FFR) and cortical auditory evoked potentials (CAEP) was accomplished in this technique by combining the use of continuous loop averaging deconvolution (CLAD) and simultaneous high resolution, long acquisition data buffers. The CLAD technique allows the recording of CAEP responses at the higher stimulation rates typically used for FFR recordings. Data from adults with normal hearing were acquired at stimulation rates of 1.95/s and 3.91/s using a 170ms, synthetic /da/ speech stimulus. The results were compared to standard FFRs and CAEP recordings. Preliminary results demonstrate the feasibility of the simE-LLR technique. The CAEP data showed the expected moderate changes in P1 and P2 latency associated with the higher stimulation rates used, but no significant amplitude changes. There was no significant difference in the FFR recordings. This new method will allow clinicians to obtain information about subcortical and cortical neural processing simultaneously and reduce the overall testing time in half, compared to separate FFR and CAEP recordings methods.

Dr. Delgado received his Ph.D. in Biomedical Engineering from the University of Miami in 1993. He is currently the Director of Research and Software Development for Intelligent Hearing System Corp. and an Adjunct Professor of Biomedical Engineering at the University of Miami. He has published extensively and developed a large number of medical products for screening and testing of hearing and vision using evoked potentials and otoacoustic emissions. He has also been the principal investigator in a large number of NIH SBIR grants for the development of these products.