Place-Based Mapping in Electric-Acoustic Stimulation Listeners

摘要 人工耳蜗(CI)植入者在植入耳内有听力障碍时，应配戴助听器。 同样的耳朵，一种被描述为电声刺激(EAS)的配置。而EAS支持更好 与仅有CI相比，这种优势在不同的人身上差别很大。一个可能的个人来源 不同之处在于CI频率与地点不匹配的可变性，这是电子设备之间的差异 分配给特定电极的滤波频率和耳蜗处的正常位置频率 那个电极。虽然先前的研究表明，单调不匹配只会影响CI中的言语感知 对于用户而言，不匹配对EAS性能的影响知之甚少。EAS中出现不匹配是因为 目前的默认映射程序使用患者在植入的耳朵中的独立听力阈值来 确定分配给电刺激的最低频率滤波器并分配较高频率 信息在其余电极上以对数方式传播，而与它们在耳蜗内的位置无关。 由于角度插入深度(AID)在横向和内部的变化很大，因此不匹配在EAS用户中很普遍 电极排列，以及残余听力的变异性。在两种情况下会发生不匹配：1)心尖电极 以声截止频率为基础，并提供低于其关联的频率信息 放置频率，或2)尖端电极位于截止频率的顶端，并传递频率信息 这比它们关联的位置频率要高。在这两种情况下，EAS的性能都可能会受到阻碍 由于刺激部位与耳蜗性的自然紧张性不匹配所致。后者的表现 这种情况可能会因外围电声掩蔽而进一步受损。然而，这些问题 如果将患者的听觉听力和电极阵列AID合并到EAS标测中，则可以避免 使用一种新的基于位置的映射程序。建议的实验评估了基于位置的映射 使用术后计算机断层扫描(CT)计算单个电极的AID的过程 确定他们的耳蜗点频率。电滤器被分配为与相关的耳蜗对准 位置频率，产生特定于患者的映射，消除了频率到位置的不匹配，并将 外围掩蔽。我们假设基于地点的地图将支持更好的单耳听力(例如语音 感知)，通过限制适应频谱移位的电子信息的需要，而 声学信息是在自然的地方传递的。此外，我们预计它将支持更好的双耳 通过提供音频信息的耳间匹配来听力(例如，从掩蔽中释放) 耳朵。基于地点的地图相对于默认地图的好处可能在以下几个月最为明显 EAS在默认情况下发生不匹配的适应时使用，并可能持续更长时间 那些错配程度最高的人。这个项目有望为一部小说和 临床可行的标测程序，以最大限度地提高EAS用户的性能。

Abstract Cochlear implant (CI) recipients with acoustic hearing in the implanted ear are fit with a hearing aid and CI in the same ear, a configuration described as electric-acoustic stimulation (EAS). While EAS supports better performance than a CI alone, the benefit varies widely across individuals. One possible source of individual differences is variability in the CI frequency-to-place mismatch, which is a discrepancy between the electric filter frequency assigned to a particular electrode and the normal cochlear place frequency at the location of that electrode. While prior studies have shown that tonotopic mismatch impacts speech perception in CI-alone users, the impact of mismatch on EAS performance is poorly understood. Mismatch in EAS occurs because current default mapping procedures use the patient’s unaided hearing thresholds in the implanted ear to determine the lowest frequency filter assigned to electric stimulation and distributes higher-frequency information logarithmically across the remaining electrodes irrespective of their location within the cochlea. Mismatch is prevalent in EAS users due to wide variability in angular insertion depth (AID) across and within electrode arrays, and variability in residual hearing. Mismatch occurs in two scenarios: 1) apical electrodes lie basal to the acoustic cut-off frequency and deliver frequency information that is lower than their associated place frequency, or 2) apical electrodes lie apical to the cut-off frequency and deliver frequency information that is higher than their associated place frequency. In both scenarios, performance with EAS is likely hindered by the mismatch between place of stimulation and natural tonotopicity of the cochlea. Performance in the latter scenario could be further compromised by peripheral electric-on-acoustic masking. However, these problems can be avoided if a patient’s acoustic hearing and electrode array AID are incorporated into EAS mapping using a novel place-based mapping procedure. The proposed experiments evaluate a place-based mapping procedure that uses postoperative computed tomography (CT) to calculate the AID of individual electrodes to determine their cochlear place frequency. The electric filters are assigned to align with the associated cochlear place frequency, resulting in a patient-specific map that eliminates frequency-to-place mismatch and minimizes peripheral masking. We hypothesize that a place-based map will support better monaural hearing (e.g. speech perception) in EAS users by limiting the need to acclimate to spectrally-shifted electric information while the acoustic information is transduced in the natural place. Further, we expect that it will support better binaural hearing (e.g. spatial release from masking) by providing an interaural match of frequency information between ears. Benefits of a place-based map over a default map will likely be most apparent during the initial months of EAS use when acclimatization to mismatch is occurring in the default case, and may persist longer-term for those with the greatest degrees of mismatch. This project is expected to lay the groundwork for a novel and clinically feasible mapping procedure to maximize performance for EAS users.