The effect of free-field presentation and processing strategy on a measure of spectro-temporal processing by cochlear-implant listeners

Abstract:

The STRIPES (Spectro-Temporal Ripple for Investigating Processor EffectivenesS) test is a psychophysical test of spectro-temporal resolution developed for cochlear implant (CI) listeners. Previously, the test has been strictly controlled to minimize the introduction of extraneous, non-spectro-temporal cues. Here, the effect of relaxing many of those controls was investigated to ascertain the generalizability of the STRIPES test. Pre-emphasis compensation was not applied to the spectrum of the STRIPES stimuli, the test was presented over a loudspeaker at a level above the automatic gain control (AGC) threshold of the CI processor, and listeners were tested using the “everyday” setting of their clinical devices. There was no significant difference in STRIPES thresholds measured across conditions for the majority of the CI listeners tested. One listener obtained thresholds above the theoretical spectral limit of performance when listening with their clinical processor. An analysis of longitudinal results showed excellent test-retest reliability over multiple listening sessions. Overall the results show that the STRIPES test is robust to extraneous cues, and that thresholds are reliable over time. Above a threshold limit defined by the filter settings of the CI processor used, no guarantee of the validity can be made of measured thresholds, and thresholds may be more variable. The STRIPES test may be sufficiently robust for use across CI manufacturers and in non-research settings.