Using current-focusing and current-steering to increase the number of effective c

描述(由申请人提供)：这项研究的总体目标是开发刺激策略，为人工耳蜗(CI)使用者增加有效渠道的数量。由于植入设备的频谱分辨率有限，大多数CI用户在挑战收听条件(例如，背景噪声、竞争语音、音乐等)方面有很大困难。当代的CI设备可以传输多达22个物理通道(以及更多的虚拟通道)，而CI用户通常只能访问~8个通道。我们假设CI用户的功能性频谱分辨率主要受通道相互作用的限制，即通道之间的电流传播。减少电流扩散的一种方法是利用三极和/或四极刺激模式(电流聚焦)。然而，即使是22个完全独立的物理频道也不足以支持具有挑战性的听力任务。将通道数量增加到超过实际电极数量的一种方法是同时刺激相邻电极，创建虚拟通道(电流控制)。我们提出了电流聚焦和电流转向相结合的方法来提高CI用户的功能频谱分辨率。如果成功，在信号处理策略中结合电流聚焦和电流控制可能允许CI用户访问困难收听条件所需的额外频谱通道。为了成功地实施这一战略，重要的是要建立电流聚焦和电流引导的基本心理物理框架。以下三个具体目标是收集制定下一代声音处理策略所需的基本信息。 在具体目标1中，我们将比较不同电流聚焦程度的响度平衡刺激之间的电流扩散。我们预测，对于固定的响度水平，聚焦刺激的电流扩散将显著减小。如果是这样的话，信号处理策略中的聚焦刺激应该减少通道相互作用并提高功能谱分辨率。在具体目标2中，我们将研究与不同程度的当前聚焦相关的知觉效应。坊间报道表明，当前的聚焦可能导致音调的变化(Saoji，2007；Berenstein，2007)和/或音调清晰度(Marzalek等人，2007)。我们预测，增加对焦将在音调清晰度方面提供微小但可靠的改善，但不会系统性地改变感知到的音调。在具体目标3中，我们将测量在有电流聚焦和没有电流聚焦的两个电极之间产生的电流控制虚拟通道的辨别度。我们预测，随着电流聚焦，虚拟通道的空间选择性将显著提高。 相关性：现代人工耳蜗术可以传输多达22个物理通道(以及更多的虚拟通道)，而听力受损的CI患者通常只能访问~8个通道。具有挑战性的收听条件(例如，噪声中的语音、竞争语音、音乐等)需要显著更多的频道。这项拟议的研究具有临床意义，因为它解决了CI研究中的一个长期挑战：如何增加有效频谱通道的数量。

DESCRIPTION (provided by applicant): The overall goal of this research is to develop stimulation strategies that increase the number of effective channels for cochlear implant (CI) users. Most CI users have great difficulty in challenging listening conditions (e.g., background noise, competing speech, music, etc.), due to the limited spectral resolution of the implant device. While contemporary CI devices can transmit as many as 22 physical channels (and many more virtual channels), CI users can typically access only ~8 channels. We hypothesize that CI users' functional spectral resolution is primarily limited by channel interactions, i.e., the electrical current spread between channels. One approach to reduce current spread is to utilize tripolar and/or quadrupolar stimulation modes (current focusing). However, even 22 fully independent physical channels are not sufficient to support challenging listening tasks. One approach to increase the number of channels beyond the physical number of electrodes is to simultaneously stimulate adjacent electrodes, creating virtual channels (current steering). We propose to combine current focusing with current steering to improve CI users' functional spectral resolution. If successful, combining current focusing and current steering within a signal processing strategy may allow CI users to access the additional spectral channels needed for difficult listening conditions. In order to successfully implement such a strategy, it is important to develop the basic psychophysical framework of current focusing and current steering. The following three specific aims are to collect the basic information needed to develop the next generation sound processing strategy. In Specific Aim 1, we will compare the current spread between loudness balanced stimuli with differing degrees of current focusing. We predict that for a fixed loudness level, current spread will be significantly reduced for focused stimuli. If so, focused stimulation in a signal processing strategy should reduce channel interaction and improve the functional spectral resolution. In Specific Aim 2, we will investigate perceptual effects associated with different degrees of current focusing. Anecdotal reports suggest that current focusing may result in changes in pitch (Saoji, 2007; Berenstein, 2007) and/or tonal clarity (Marzalek et al., 2007). We predict that increased focusing will provide a small but reliable improvement in tonal clarity, but will not systematically alter the perceived pitch. In Specific Aim 3, we will measure discrimination of current-steered virtual channels that can be generated between two electrodes with and without current focusing. We predict that spatial selectivity for virtual channels will be significantly improved with current focusing. Relevance: While contemporary cochlear implants (CIs) can transmit as many as 22 physical channels (and many more virtual channels), hearing impaired patients with CIs can typically access only ~8 channels. Challenging listening conditions (e.g., speech in noise, competing speech, music, etc) require significantly more channels. The proposed research is clinically relevant, as it addresses a long-standing challenge in CI research: how to increase the number of effective spectral channels.