1Department of Audiology and Speech Pathology, The University of Melbourne, Melbourne, Victoria, Australia; 2The Hearing Cooperative Research Centre, Melbourne, Victoria, Australia; and 3Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.
Ear Hear. 2017 Nov/Dec;38(6):e325-e334. doi: 10.1097/AUD.0000000000000442.
To measure binaural benefit over the shadowed ear alone for young bilateral cochlear implant (CI) users. It was hypothesized that children who received bilateral CIs at a young age (<4 years), and had significant bilateral experience, would demonstrate lower detection thresholds for speech sounds in background noise in the bilateral CI over the unilateral CI condition when the added CI was ipsilateral to the noise source.
Children receiving bilateral CIs at the Eye and Ear Hospital Clinic in Melbourne were invited to participate in a wider research project evaluating outcomes; those participating in the wider project who were bilaterally implanted by 4 years and were approximately 2 years postoperative were included in the present study. For 20 participants, detection signal to noise ratios (SNRs) were measured for speech presented from in front and noise from 90° in at least 3 of 4 device/noise conditions, namely left CI/noise right and right CI/noise left, plus bilateral CIs/noise right and bilateral CIs/noise left.
As some participants could only complete testing in 3 conditions within the 1 test block, the unilateral versus bilateral comparison was performed for 1 CI (i.e., 1 noise direction) for 15 participants and for both CIs (i.e., noise left and noise right) for 5 participants. Group analysis indicated no significant difference in detection SNR between the unilateral and bilateral CI conditions when adding the left CI or right CI (for the overall group) or when adding the first or second CI (for the 15 participants with sequential bilateral CIs). Separate analyses indicated no significant difference in detection SNR between the unilateral and bilateral CI conditions for the majority of individuals; this occurred irrespective of whether the analysis indicated that the CI added in the bilateral condition was poorer-performing, better-performing, or not significantly different compared with the other CI. Four individuals demonstrated a significant improvement in the bilateral condition when the CI added in the bilateral condition was a better-performing (n = 1), poorer-performing (n = 2), or not significantly different CI (n = 1). There was no relationship between the detection SNR difference between each CI and the detection SNR difference between the unilateral and bilateral conditions.
The hypothesis of a lower detection SNR in the bilateral condition was not supported by the group results or by the results for the majority of individuals. For the 4 participants who did demonstrate benefit over the shadowed ear alone, that benefit cannot be separated from the potential benefit gained as a result of the CI added in the bilateral condition being the better-performing CI for 1 of the 4. Variation in outcomes could not be related to demographic factors for this group, which was relatively homogeneous for age at bilateral CI and experience; an older, more experienced group may demonstrate greater binaural benefit in these conditions. These results can be used during counseling for families regarding postoperative expectations for young children, especially in the first 2 years.
测量年轻双侧人工耳蜗植入（CI）使用者单侧 CI 下的双耳优势。假设在 4 岁之前接受双侧 CI 且具有双侧显著经验的儿童，当添加的 CI 同侧噪声源时，在双侧 CI 条件下，双侧 CI 对噪声中的语音的检测阈值将低于单侧 CI 条件。
墨尔本眼耳医院诊所的双侧 CI 接受者被邀请参加更广泛的研究项目评估结果；那些参与更广泛项目的双侧植入者在 4 岁之前，术后约 2 年被纳入本研究。对于 20 名参与者，在至少 3 种 4 种设备/噪声条件下（即左 CI/噪声右和右 CI/噪声左，加上双侧 CI/噪声右和双侧 CI/噪声左）测量了语音的检测信号噪声比（SNR）。
由于一些参与者在 1 个测试块中只能完成 3 种条件的测试，因此对于 15 名参与者中的 1 个 CI（即 1 个噪声方向）和 5 名参与者中的两个 CI（即噪声左和噪声右）进行了单侧与双侧 CI 条件的比较。组分析表明，当添加左 CI 或右 CI（对于整个组）或添加第一或第二 CI（对于具有顺序双侧 CI 的 15 名参与者）时，双侧 CI 条件与单侧 CI 条件之间的检测 SNR 没有显著差异。单独分析表明，对于大多数个体，双侧 CI 条件与单侧 CI 条件之间的检测 SNR 没有显著差异；这与分析表明双侧条件下添加的 CI 性能较差、性能较好或与另一个 CI 无显著差异无关。当双侧条件下添加的 CI 性能较好、较差或无显著差异时，有 4 名个体的双侧条件下的检测 SNR 有显著改善（n=1），性能较差（n=2），或无显著差异 CI（n=1）。每个 CI 之间的检测 SNR 差异与单侧和双侧条件之间的检测 SNR 差异之间没有关系。
组结果或大多数个体的结果均不支持双侧条件下检测 SNR 降低的假设。对于单侧 CI 下表现出优势的 4 名参与者，这种优势不能与由于双侧条件下添加的 CI 成为 4 名参与者中更好的 CI 而获得的潜在优势分开。对于这组个体，结果的变化不能与年龄在双侧 CI 方面和经验方面相对同质的人口统计学因素相关，年龄较大、经验更丰富的组可能在这些条件下表现出更大的双耳优势。这些结果可用于为家庭提供有关年轻儿童术后预期的咨询，尤其是在前 2 年。
