FREE ABSTRACTS Comparing Cochlear Implant Users' Speech Performance with Processor Fittings Based on Conventionally Determined T and C Levels or on Compound Action Potential Thresholds and Live- Voice Speech in a Prospective Balanced Crossover

Objective: The objective of the present study is to improve the efficiency of the fitting procedure of cochlear implant processors by making use of measurements of the electrically evoked compound actio potential (ECAP) and live-voice speech. Design: In a randomised prospective cross-over design we compare speech performance of eighteen adult subjects when following the conventional fitting procedure to a procedure in which we use the profile of the ECAP threshold levels across the full electrode array measured intra-operatively. The overall level of the profile is shifted (by an equal amount of current units per electrode) until we find the threshold for live speech (new T levels) and the loudness comfort level (new C levels). Each fitting procedure is tested for 6 wk. Speech performance is measured in quiet and in noise every other week. Results: The results show little difference between the scores (Dutch CVC words) for the conventional fitting procedure and the ECAP based fitting, although the T and C levels may differ markedly. Conclusion: The new fitting procedure is much faster and easier in the initial phase. Further improvement of performance may be obtained in a later stage of the fitting procedure by changing some individual electrodes on the basis of subjective responses. Wideband Reflectance Norms for Caucasian and Chinese Young Adults. Ear & Hearing. 27(6):774-788, December 2006. Navid Shahnaz; Karin Bork Abstract: Objective: This study examined differences between the middle ears of two ethnic groups, Caucasian and Chinese young adults with normal hearing, using a new middle-ear measurement technique, wideband energy reflectance. The goal of this study was to determine whether the Chinese group had different middleear transmission properties than the Caucasian group. Objective: This study examined differences between the middle ears of two ethnic groups, Caucasian and Chinese young adults with normal hearing, using a new middle-ear measurement technique, wideband energy reflectance. The goal of this study was to determine whether the Chinese group had different middleear transmission properties than the Caucasian group. Design: There were 126 subjects (237 ears) between the ages of 18 and 32 yr, with 62 subjects in the Caucasian group and 64 subjects in the Chinese group. Wideband energy reflectance data were gathered using Mimosa Acoustics (RMS system version 4.0.4.4) wideband reflectance (WBR) equipment. Results: The Chinese group had significantly lower wideband energy reflectance than their Caucasian counterparts at higher frequencies; however, the Caucasian group had significantly lower energy reflectance at lower frequencies than the Chinese group. The Chinese group also had significantly lower admittance magnitude than the Caucasian group at lower frequencies. Because body size indices are more comparable between Caucasian females and Chinese males, the effect of body size could be potentially adjusted for by comparing the Caucasian female subjects with the Chinese male subjects. The differences observed between the Caucasian and the Chinese groups were no longer significant when the Caucasian female subjects were compared with the Chinese male subjects. Applying the Caucasian norms to four Caucasian adults with surgically confirmed otosclerosis resulted in an improved hit rate compared with the combined Caucasian and Chinese norms and the Chinese-only norms.