This project aims to develop a device capable of acquiring transient and steady state auditory evoked potenlatials (AEPs) simultaneously using an efficient and advanced processing technique. The proposed technique will be implemented as a software module on Intelligent Hearing Systems'(IHS) evoked potential system platform. Auditory Transient Responses (ATRs) are typically elicited using short duration stimuli and include Auditory Brainstem Responses (ABRs), Middle Latency Responses (MLRs) and Late Latency Responses (LLRs). Auditory Steady State Responses (ASSRs) are elicited using long duration stimuli and represent continuous evoked activity. Currently, ATR and ASSR data are recorded independently, using either different software modules or different devices, and the resulting data are analyzed and presented independently. As a result, testing time is prolonged and it may be difficult to reconcile data because of differences in stimulation technique, calibration and patient status between tests. A new method of acquiring ATRs and ASSRs simultaneously has been developed by Intelligent Hearing Systems. The technique uses sets of special stimulation sequences that can be deconvolved to extract ATRs while averaging the sets together results in true ASSRs. Unlike previous deconvolution techniques, such as Maximum Length Sequences (MLS), which required complex non-periodic stimuli for deconvolution, the proposed technique uses a more recently developed method, Continuous Loop Averaging Deconvolution (CLAD), which utilizes nearly isosynchronous sequences. By combining sets of nearly isosynchrnous sequences, the simultaneous acquisition of ATRs and ASSRs is accomplished. The benefits of acquiring both ATRs and ASSRs simultaneously are numerous: 1) Provide unique information from each type of response without increasing test time, 2) Eliminate patient state differences between recording procedures, 3) Eliminate problems associated with use of different stimuli and calibration, and 4) Facilitate interpretation of data by providing all results on one user interface. During Phase I, work will be conducted to optimize and test the proposed simultaneous technique by comparing results with conventional ATRs and ASSRs using click and frequency specific stimuli on 10 young adult subjects. During Phase II, the work will be expanded and a larger clinical study conducted including infants and adults of various hearing loss configurations. The device is expected to have immediate commercialization potential as an add-on software module for the thousands of current IHS users and new potential users as well.
The ability to acquire both auditory transient and steady state evoked potentials at the same time will provide a great benefit to patients and clinicians. The proposed technique will reduce testing time and allow for easier interpretation of results by assuring that data were acquired using the same stimulus and calibration levels, and same patient state. As such, the proposed work will greatly impact public health by developing better hearing diagnostic systems.