Localization and Speech Intelligibility in EAS and Bilateral CI Users

描述（由申请人提供）：直到最近，大多数人工耳蜗都是单侧的。然而，现在有两组植入患者可以使用来自两只耳朵的相同输入。一组使用双侧人工耳蜗（CI）。这些人有两个CI，没有残余听力（双侧CI）。另一组在植入耳中保留低频声学听力，对侧耳也保留低频声学听力。这些患者在植入耳内结合电和声刺激（EAS），对侧有残留的低频听力。他们可以接触到双边低频声信号，被称为EAS。(EAS不同于双模CI使用者，双模CI使用者在单耳通过CI进行电刺激，并在CI的对侧进行声学听力。换句话说，双峰CI用户的每只耳朵都有不同的听力。)我们可以使用双侧CI和EAS两组不同类型双侧听力的患者来评估耳间水平差（ILD）线索和耳间时差（ITD）线索在定位和真实世界环境下的言语理解中的价值。耳际时间和强度差异为正常听者提供了定位能力，并被认为是掩蔽空间释放（SRM）的基础。迄今为止，只有一篇关于EAS用户本地化的论文（Dunn et al., 2010）。Dunn报告说，EAS用户能够定位，尽管不如正常听力的听众。然而，这项研究缺乏对用于定位的频率信息的控制。有一种共识认为，双边用户具有ILD敏感性，但无法获得过渡段的线索（Grantham等人，2007）。Loizou等人（2009）报告称，双边CI用户不会从掩蔽的空间释放中受益，可能是由于缺乏过渡段提示。如果在真实世界的噪声环境中，ITD线索对于SRM是必要的，那么EAS患者在这些环境中可能比双侧CI患者受益更多。本研究的具体目的是确定(i)哪一种潜在机制，过渡段、ILD或两者，是两组定位的基础；（ii）当CI听者被置于困难的现实听力环境中时，过渡段或ILD线索是否提供了更大的优势；（iii）耳间过渡段和ILD线索的可用性与SRM之间是否存在关系。这些问题的答案将塑造我们对人工耳蜗益处的理解，并为患者提供有关人工耳蜗在现实世界中的益处的信息。本研究设计了一个2（组=双侧CI和EAS） x3（低通、高通、宽带噪声）重复测量方差分析来评估三种噪声条件下的定位能力，以及一个2（组=双侧CI和EAS） x2（聆听模式和噪声条件）重复测量方差分析来评估噪声下的语音感知。将计算分析以确定定位性能是否与屏蔽的空间释放相关。

DESCRIPTION (provided by applicant): Until relatively recently, most cochlear implants were unilateral. Now, however, there are two groups of implant patients who can use the same kind of input from two ears. One group uses bilateral cochlear implants (CI). These individuals have two CIs with no residual hearing (Bilateral CI). Another group has preserved low- frequency acoustic hearing in the implanted ear and also has acoustic low-frequency hearing in the contralateral ear. These patients combine electric and acoustic stimulation (EAS) in the implanted ear and have residual low frequency hearing contralaterally. They have access to bilateral low frequency acoustic cues and are referred to as EAS. (EAS are different than bimodal CI users who have electric stimulation in one ear via a CI and acoustic hearing contralateral to the CI. In other words bimodal CI users have different hearing in each ear.) We can use these two groups of patients, Bilateral CI and EAS, with different types of bilateral hearing to assess the value of interaural level difference (ILD) cues and interaural time difference (ITD) cues in localization and in speech understanding in real world environments. Interaural time and intensity differences are known to provide normal hearing listeners with the ability to localize and are thought to underlie spatial release from masking (SRM). To date, there is a single paper (Dunn et al., 2010) on localization in EAS users. Dunn reported that EAS users are able to localize although not as well as normal hearing listeners. The study, however, lacked controls for the frequency information used in localization. There is a consensus that bilateral users have ILD sensitivity but do not have access to ITD cues (Grantham et al., 2007). Loizou et al. (2009) report bilateral CI users do not benefit from spatial release from masking, presumably due to the absence of ITD cues. If ITD cues are necessary for SRM in real world noise environments, EAS patients may benefit more in these environments than bilateral CI patients. The specific aims of this research are to determine (i) which underlying mechanism, ITD, ILD or both, underlie localization by the two groups, (ii) whether ITD or ILD cues provide a greater advantage when CI listeners are placed in difficult real world listening situations, and (iii) if there is a relationship between the availability of interaural ITD and ILD cues and SRM. The answers to these questions will shape our understanding of cochlear implant benefit and provide information to patients about real world benefits of CIs. The research design is a 2(groups=bilateral CI and EAS) X 3 (low-pass, high-pass, wideband noise) repeated measures ANOVA for localization ability from the three noise conditions and a 2 (groups = bilateral CI and EAS) X 2 (mode of listening and noise condition) repeated measures ANOVA for speech perception in noise. An analysis will be calculated to determine if performance on localization correlates with spatial release from masking. PUBLIC HEALTH RELEVANCE: The implications for a potential cochlear implant patient who is trying to decide between bilateral versus EAS could justifiably impact the decision of the patient, the surgeon, the audiologist, the tax payers, and even the insurance companies. This information will provide potential CI users and hearing health care providers with the necessary information to make an informed decision regarding expected outcomes.