Developing a Flexible SPEAR3-Based Psychophysical Research Platform for Testing Cochlear Implant Users

An experimental psychophysical interface has been developed using Hearworks Pty Ltd’s SPEAR3 research sound processor, which is compatible with Cochlear Corporation’s Nucleus CI22 and CI24 implants. Modifications to the assembly code program file that resides in the SPEAR3 allow the parameters of a given stimulus to be updated on a trial-by-trial basis due to the responses given by a cochlear implant subject through a Visual Basic graphical user interface. Using a single program for the digital signal processor, this graphical user interface may be tailored to perform both traditional and original psychophysical experiments. The research sound processor also allows implementations of novel sound processing algorithms. Threshold and maximum comfort levels were measured with the SPEAR3, and one subject’s levels were compared to those measured with the commercially available Nucleus Implant Communicator (NIC v2). No significant difference was found. Three cochlear implant subjects performed a rate discrimination task using the SPEAR3-based experimental interface, and the trends found in the resulting data imply that the SPEAR3-based experimental interface is functioning properly and may be used in the future for other psychophysical investigations.