From TEMPO+ to OPUS 2: what can music tests tell us about processor upgrades?

Tests for quantifying the music perception abilities of cochlear implant users are currently being developed and trialled at the South of England Cochlear Implant Centre. In addition to measures of speech perception, tests of rhythm, and pitch have been administered to MED-EL C40+ implant users before and after upgrading from the TEMPO+ processor with continuous interleaved sampling strategy to the OPUS 2 processor with fine structure processing strategy, with the aims of comparing device performance and evaluating the potential of music perception tests for informing processor upgrades and tuning. Eight experienced adult C40+ implant recipients performed tests of rhythm and pitch discrimination using the TEMPO+ processor and, after a minimum of 6 weeks acclimatization, using the OPUS 2 processor. Stimuli included piano and sine tones in two note ranges for the pitch tasks, and drum beats for the rhythm task. Rhythm, pitch, and speech perception scores were comparable for both processors. An effect of note range was observed (z = -2.52, p = 0.008 (two-tailed), r = -0.63), which indicated that the higher range of notes used for the pitch tasks was easier for participants than the lower range. Measures of pitch discrimination in different frequency ranges further informed changes made to one participant's map, resulting in improved pitch discrimination and speech perception scores. The outcomes of this study demonstrate that music perception tests can provide important additional measures for tuning cochlear implant parameters and assessing the impact of changes to device type and processing strategy.