Determining cochlear implant users' true noise tolerance: use of speech reception threshold in noise testing

Abstract

OBJECTIVE: The speech perception abilities of cochlear implant (CI) recipients have significantly improved over the past decade. At the same time, clinical test batteries to measure their performance in noise remain mostly unchanged, resulting in ceiling-level performance for the most successful recipients. The goal of this study is to determine the true noise tolerance abilities of CI recipients using adaptive speech reception threshold (SRT) in noise testing. STUDY DESIGN: Prospective clinical study. SETTING: Tertiary care hospital; CI program. PATIENTS: Ten CI users, either unilateral or bilateral, with HINT scores that equaled or exceeded 80% when administered with a fixed +10 dB signal-to-noise (SNR) ratio (i.e., HINT(+10dB)). INTERVENTION: The HINT with adaptive SNR levels and QuickSIN test were administered to measure noise tolerance at speech thresholds where 50% of the stimuli were correctly perceived. MAIN OUTCOME MEASURE(S): SRTs were measured for both the adaptive SNR HINT (i.e., HINT(50%)) and the QuickSIN test. These SRTs were compared with the fixed noise level HINT(+10dB) scores as well as to CNC monosyllable word perception scores. RESULTS: Despite small variance in performance levels on the HINT(+10dB), results of the HINT(50%) ( approximately 16 dB range) and QuickSIN ( approximately 12 dB range) tests demonstrate significant differences in noise tolerance levels among these CI recipients. CONCLUSION: For excellent CI users, use of adaptive speech threshold tests in noise better defines a user's actual ability to perceive speech than do fixed SNR level tests. SRT-in-noise tests have the advantage of being quick to administer, and the same stimuli can be used over a very wide range of performance levels. The use of adaptive SRT-in-noise tests should be considered a viable and valuable replacement of fixed SNR tests in the CI clinical test battery.