Frequency-Place Mapping in Cochlear Implants

人工耳蜗中的频率位置映射

• 批准号: 6862792
• 负责人: Robert V Shannon
• 金额: $ 34.01万
• 依托单位: HOUSE RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-05-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6862792
• 关键词: auditory discrimination; clinical research; cochlear implants; computational neuroscience; electrodes; electrostimulus; hearing aids; human subject; mathematical model; medical implant science; model design /development; neural information processing; noise; sound frequency; speech recognition

Cochlear implants (CI) are now in widespread use and the average performance level is excellent, but there is considerable variability in performance across patients. The 1995 NIH Consensus Conference on Cochlear Implants identified variability in patient outcomes as one of the key areas in need of further research. Recent research in our lab has shown little variability in performance across normal-hearing listeners tested with the same signal processing as CI listeners. Our overall hypothesis is that this variability is partly (or even largely) due to poor fitting of the processor parameters to the individual patient, particularly in the frequency domain. Experiments on normal-hearing listeners show that warping the frequency-to- cochlear place assignments can result in a large degradation in performance. Our overall goal is to develop a quantitative model of the effects of frequency-place mismatching, which could be used to guide the fitting of speech processors in cochlear implants and hearing aids. Specific Aim 1 is to quantify the effects of various types of distortion in the frequency-place mapping on speech recognition in quiet and in noise. Distortions to be characterized are: frequency-place shifts, truncation in acoustic or cochlear domains, and linear and nonlinear frequency-place warping. We will measure phoneme, word and sentence cognition as a function of the signal-to-noise ratio [performance-intensity (PI) functions]. Simple sigmoidal functions will be fit to the PI functions and the three parameters [speech recognition threshold (SRT), slope, and asymptote] will be estimated as a function of the independent variable. Specific Aim 2 is to assess the differences between CIS, SAS, and n-of-m processing strategies. One experiment will directly compare performance in the same NH and CI listeners for CIS and n-of-m processors. Another experiment will assess place-specific temporal processing in SAS processors and the results will be compared to CIS and n-of-m processing with the same frequency- place map. Specific Aim 3 is to develop a mathematical model of the effects of various types of distortions in the frequency-place mapping, based on the data obtained in Aim 1. This model would define a multidimensional surface relating speech recognition as a function of signal-to-noise level to frequency-place mapping parameters. The model would provide a quantitative description of this parameter space and would provide the basis for frequency-place parameter optimization strategies. Parameter optimization procedures (Simplex, Neural Networks, Genetic algorithms) will then be applied to this surface to find the frequency-place (or frequency-electrode) assignment that produces maximum performance.

髋关节植入物（CI）目前已被广泛使用，平均性能水平极佳，但患者之间的性能差异相当大。 1995年美国国立卫生研究院共识会议上的植入物确定的变异性，患者的结果作为一个关键领域，需要进一步研究。 我们实验室最近的研究表明，使用与CI听众相同的信号处理进行测试的正常听力听众的性能变化很小。 我们的总体假设是，这种变异性部分（甚至很大程度上）是由于处理器参数与个体患者的拟合不良，特别是在频域中。 对听力正常的听众进行的实验表明，扭曲频率到耳蜗的位置分配可能会导致性能大幅下降。 我们的总体目标是建立一个频率-位置失配效应的定量模型，该模型可用于指导人工耳蜗和助听器中语音处理器的安装。具体目标1是量化在安静和噪声中的语音识别的频率-位置映射中的各种类型的失真的影响。 失真的特点是：频位移位，截断在声学或耳蜗域，线性和非线性频位翘曲。 我们将测量音素，单词和句子认知作为信噪比的函数[性能强度（PI）函数]。 简单的S形函数将拟合PI函数，三个参数[语音识别阈值（SRT）、斜率和渐近线]将作为自变量的函数进行估计。具体目标2是评估CIS、SAS和n-of-m处理策略之间的差异。 一个实验将直接比较CIS和n-of-m处理器在相同NH和CI侦听器中的性能。 另一个实验将评估SAS处理器中特定于地点的时间处理，并将结果与具有相同频率-地点图的CIS和n-of-m处理进行比较。具体目标3是根据目标1中获得的数据，建立频率-位置映射中各种类型失真影响的数学模型。 这个模型将定义一个多维表面相关的语音识别作为一个函数的信号噪声水平的频率位置映射参数。 该模型将提供该参数空间的定量描述，并将提供频率-位置参数优化策略的基础。 然后将参数优化程序（单纯形、神经网络、遗传算法）应用于该表面，以找到产生最大性能的频率-位置（或频率-电极）分配。