An approach to develop an objective measure of temporal processing in cochlear implant users based on Schroeder-phase harmonic complexes

Recent evidence suggests that cortical auditory evoked potentials recorded by EEG may be used to obtain an objective measure of spectral sound processing abilities in cochlear implant (CI) users. As speech perception depends on both spectral and temporal processing abilities, developing an objective measure of sound processing in the temporal domain is necessary for a complete evaluation of CI speech performance. This study explored the feasibility to objectively assess sound processing in the temporal domain employing a method based on EEG and complex temporal stimuli such as the Schroeder-phase harmonic complexes. Psychoacoustic discrimination abilities were measured employing a four-interval two-alternative forced choice paradigm. Neural discrimination abilities were measured by recording single-channel EEG during an unattended oddball paradigm. Psychoacoustic and neural discrimination abilities were analyzed for correlation. A strong, but non-significant, correlation was found in three out of six subjects. Schroeder-phase harmonic complexes may have utility as stimuli in the development of an objective measure of temporal processing in CI users. Furthermore, they provide new insights on temporal processing in CI users that may benefit the development of the CI.