Adaptation to frequency mismatch in cochlear implant users

描述(由申请人提供)：人工耳蜗(CI)利用耳蜗声强直的结构，随着输入声音频率的增加，刺激区域逐渐接近基底部。CI中的一个关键拟合参数是频率表，在该表中，输入的声频率被分配给耳壳内电极。在目前的临床实践中，给定CI模型的所有用户收到的频率表基本相同。在语言后听力受损的CI用户中，这种一刀切的方法可能会在输入声频和被刺激的神经元的特征频率之间引入不匹配。尽管人类听众可以适应这些扭曲，但越来越多的证据表明，有时这种适应过程可能是不完整的。在语言后听障CI人群中，适应过程及其可能的不完全性都对言语知觉产生重要影响。拟议工作的第一个目标是衡量这一适应过程的程度和时间进程，这将在两个实验中进行探索。实验1将研究最近植入的CI使用者，并对他们进行为期一年的跟踪，使用四种不同的方法来衡量对频率不匹配的适应，并辅之以一系列语音感知、心理物理、认知和解剖学测量。实验二将考察相同的问题，但对象是一组有长期工作经验(至少一年)的CI用户。这两个实验还有第二个目标：使用解剖学和认知测量来预测哪些人更有可能对他们的临床频率表不完全适应。最后，实验3将解决本研究的第三个目标：检验旨在减少频率失配的频率表将提高不完全适应的CI使用者的言语知觉分数的假设。拟议工作的一部分涉及开发和改进软件和硬件工具，以便利寻找可能有助于最大限度地减少频率不匹配的替代频率表。总之，这项建议中描述的实验将为语言后听力受损的CI用户对修改后的外周频率图的听觉适应的性质提供新的见解，并将为负责安装这些设备的临床医生提供指导。像现在这样的研究将有助于将基础知识转化为临床实践，并将使临床实践更多地由数据和理论驱动。 与公共健康相关：这项拟议的研究旨在了解人类听众如何适应他们听觉频率图中的扭曲。这一知识可能有助于改善人工耳蜗用户的语音感知，这些用户难以适应编程到他们的语音处理器中的标准频率表。该项目还旨在开发硬件和软件工具，使这些科学发现能够转化为实际的临床实践。

DESCRIPTION (provided by applicant): Cochlear implants (CIs) take advantage of the tonotopic structure of the cochlea, stimulating areas progressively closer to the base as the input sound frequency increases. One key fitting parameter in a CI is the frequency table wherein input acoustic frequencies are allocated to intracochlear electrodes. Under current clinical practice, all users of a given CI model receive basically the same frequency table. In postlingually hearing impaired CI users, this one-size-fits-all approach may introduce mismatches between input acoustic frequency and the characteristic frequency of the neurons that are stimulated. Although human listeners can adapt to these distortions, there is growing evidence that sometimes this adaptation process may be incomplete. Both the adaptation process and its possible incompleteness have important consequences to speech perception in the postlingually hearing impaired CI population. The first aim of the proposed work is to measure the extent and the time course of this adaptation process, which will be explored in two experiments. Experiment 1 will study recently implanted CI users and follow them for a year, using four different methods to measure adaptation to frequency mismatch, complemented by a battery of speech perception, psychophysical, cognitive, and anatomical measurements. Experiment two will examine the same questions but with a group of CI users with long term experience (at least one year). Both experiments will also have a second aim: using the anatomical and cognitive measures to predict which individuals are more likely to suffer incomplete adaptation to their clinical frequency tables. Lastly, Experiment 3 will address the third aim of the proposed research: to test the hypothesis that frequency tables intended to reduce frequency mismatch will improve speech perception scores in those CI users who show incomplete adaptation. Part of the proposed work involves developing and refining software and hardware tools to facilitate the search for alternative frequency tables that may help minimize frequency mismatch. In summary, the experiments described in this proposal will provide new insights about the nature of auditory adaptation to a modified peripheral frequency map by postlingually hearing impaired CI users, and will also provide guidance to the clinicians who are in charge of fitting these devices. Studies like the present ones will help translate basic knowledge into clinical practice, and will make clinical practice more data- and theory-driven. PUBLIC HEALTH RELEVANCE: The proposed research aims to understand how human listeners adapt to distortions in their auditory frequency maps. This knowledge may help improve speech perception in cochlear implant users who have difficulty adapting to the standard frequency tables programmed into their speech processors. The project also aims to develop the hardware and software tools that will allow the translation of these scientific findings into actual clinical practice.