Eaton-Peabody Laboratories Cochlear Function Testing
EPL Engineering, supported by a P30 grant from the NIDCD, has designed and implemented a new system for Signal Generation / Data Acquisition (SG/DAQ) that requires minimal custom hardware and is powerful enough to meet the most demanding needs in auditory neuroscience, yet inexpensive enough to be affordable for the less-demanding application. This SG/DAQ system, consisting of National Instruments digital I/O boards in a fast PXI chassis, has clean, 24-bit outputs and inputs, with user-accessible signal grounds isolated from the embedded computer, allowing stimulus synthesis and response measurement over the entire dynamic range of hearing. For more information about the SG/DAQ system architecture, download the EPL PXI System Overview.
EPL Engineers and Investigators have developed the Cochlear Function Test Suite to allow flexible control of the EPL PXI SG/DAQ for stimulus and averaging parameters in the measurement of amplitude-vs-level functions for ABRs, CAPs, DPOAEs, and VsEPs as well as a CAP-Threshold function that tracks, across frequency, the SPL required to produce a CAP of criterion magnitude. The software also includes subroutines for rapid, densely sampled acoustic calibration, including measuring probe-tube microphone sensitivity against a calibrated microphone in a coupler, and sound pressure produced by each earphone in situ. For more information on this software package, see the Cochlear Function Test Suite Users' Manual. For instructions on configuring the EPL PXI system to run this software, see the EPL PXI Configuration Manual.
EPL Engineering continues to improve the performance of the EPL Acoustic Assembly, a two-source acoustic system for calibrated sound delivery with low distortion and high output (>100 dB SPL) to frequencies > 60 kHz. The system uses inexpensive miniature dynamic earphones to generate stimuli and a miniature high-frequency microphone to monitor sound pressure via a probe tube, all housed in a plastic assembly that can be produced via stereolithography from a downloadable computer file. For full assembly instructions, see the EPL Acoustic System Assembly Manual.