Multicenter surgical experience evaluation on the Mid-Scala electrode and insertion tools.

The HiFocus Mid-Scala electrode is intended to improve hearing for individuals with severe-to-profound hearing loss by providing extended electrical coverage of the cochlea while minimizing trauma related to insertion. The electrode is appropriate for use with a wide range of surgical techniques, including either a cochleostomy or round window insertion, and the use of either a free-hand or tool-assisted approach. The objective of this survey was to evaluate how the HiFocus Mid-Scala electrode and insertion tools was used across a population of cochlear implant recipients of differing ages, audiologic profiles, and anatomical characteristics. The intent was to understand the type and frequency of surgical techniques applicable with the electrode, and to provide guidelines for clinical practice. Two questionnaires were completed by surgeons at implant centres located in the United States, Europe, and Asia. Before any surgeries were conducted, surgeons completed a questionnaire that assessed their overall cochlear implant surgical practice and preferences. Following each HiFocus Mid-Scala electrode insertion, surgeons completed a questionnaire that summarized their experience during that surgical procedure. Questionnaires were completed by 32 surgeons from 16 centres for a total of 143 surgeries (112 adults, 31 children). Most surgeons (62 %) preferred to insert the electrode via the round window or an extended round window compared with a cochleostomy (16 %), whereas the remaining 22 % indicated that they made an insertion choice based on presenting anatomy. Sixty-nine percent preferred a free-hand approach over using insertion tools. In 32 procedures, surgeons elected to deviate from an intended round window insertion to either an extended round window or cochleostomy approach.

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

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%) (∼16 dB range) and QuickSIN (∼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.

A predictive model of cochlear implant performance in postlingually deafened adults.

OBJECTIVE: To develop a predictive model of cochlear implant (CI) performance in postlingually deafened adults that includes contemporary speech perception testing and the hearing history of both ears. STUDY DESIGN: Retrospective clinical study. Multivariate predictors of speech perception after CI surgery included duration of any degree of hearing loss (HL), duration of severe-to-profound HL, age at implantation, and preoperative Hearing in Noise Test (HINT) sentences in quiet and HINT sentences in noise scores. Consonant-nucleus-consonant (CNC) scores served as the dependent variable. To develop the model, we performed a stepwise multiple regression analysis. SETTING: Tertiary referral center. PATIENTS: Adult patients with postlingual severe-to-profound HL who received a multichannel CI. Mean follow-up was 28 months. Fifty-five patients were included in the initial bivariate analysis. INTERVENTION(S): Multichannel cochlear implantation. MAIN OUTCOME MEASURES(S): Predicted and measured postoperative CNC scores. RESULTS: The regression analysis resulted in a model that accounted for 60% of the variance in postoperative CNC scores. The formula is (pred)CNC score = 76.05 + (-0.08 x DurHL(CI ear)) + (0.38 x pre-HINT sentences in quiet) + (0.04 x long sev-prof HL(either ear)). Duration of HL was in months. The mean difference between predicted and measured postoperative CNC scores was 1.7 percentage points (SD, 16.3). CONCLUSION: The University of Massachusetts CI formula uses HINT sentence scores and the hearing history of both ears to predict the variance in postoperative monosyllabic word scores. This model compares favorably with previous studies that relied on Central Institute for the Deaf sentence scores and uses patient data collected by most centers in the United States.

Spectral modulation detection as a function of modulation frequency, carrier bandwidth, and carrier frequency region.

The present study investigates the nature of spectral envelope perception using a spectral modulation detection task in which sinusoidal spectral modulation is superimposed upon a noise carrier. The principal goal of this study is to characterize spectral envelope perception in terms of the influence of modulation frequency (cycles/octave), carrier bandwidth (octaves), and carrier frequency region (defined by lower and upper cutoff frequencies in Hz). Spectral modulation detection thresholds measured as a function of spectral modulation frequency result in a spectral modulation transfer function (SMTF). The general form of the SMTF is bandpass in nature, with a minimum modulation detection threshold in the region between 2 to 4 cycles/octave. SMTFs are not strongly dependent on carrier bandwidth (ranging from 1 to 6 octaves) or carrier frequency region (ranging from 200 to 12 800 Hz), with the exception of carrier bands restricted to very low audio frequencies (e.g., 200-400 Hz). Spectral modulation detection thresholds do not depend on the presence of random level variations or random modulation phase across intervals. The SMTFs reported here and associated excitation pattern computations are considered in terms of a linear systems approach to spectral envelope perception and potential underlying mechanisms for the perception of spectral features.