Restoring binaural hearing abilities to bilateral cochlear implant users

 描述(申请人提供)：虽然人工耳蜗已经成功地使严重到严重听力损失的人能够进行语音理解，但在定位声音方向和在噪音中理解语音等任务中的表现仍然具有挑战性。这些任务在听力正常的人中得到了双耳听力的帮助，但双侧人工耳蜗术并没有提供同样程度的好处。这种缺陷很大程度上源于现代人工耳蜗术(CI)中声音转化为电刺激的方式。现代CI通过将输入声学信号分成多个通道并用恒定的高速率电脉冲序列对每个通道进行编码来操作。众所周知，这种处理会影响对耳间时间差(ITDS)的敏感度，ITDS是一种在嘈杂环境中对声音定位和语音理解很重要的双耳CU。在双边CI使用者中，存在一个难题，即在低刺激率下出现良好的ITD敏感性，但更好的语音理解需要高刺激率。建议的解决方案通常混合不同通道的刺激率，其中在低频通道中使用低速率，而在高频通道中使用高速率。这种方法假设，在正常听力听者中，ITDS是低频的主要线索，应该出现在耳蜗对低频最敏感的地方。然而，双边CI用户对ITD敏感性的测量表明，这一假设不一定成立，这表明可以考虑用替代方法在CI中呈现ITD。这项研究的目的是测量在高速电脉冲序列中编码的带限频率调制(FM)在多大程度上可以提高双边CI用户的双耳听力。与使用混合刺激率的解决方案相比，编码FM的新奇之处在于，ITD提示可以在所有通道上呈现，从而使所有CI用户的ITD灵敏度最大化。这项工作的目标将是证明使用调频编码来改善双边CI用户的双耳听力的可行性，这一结果迄今尚未实现。我们的重点将是确定在双边CI用户中最大化ITD灵敏度的最佳FM参数。提高双边CI使用者的双耳听力将对他们在日常听力情景中的互动方式产生积极影响，通过减少在嘈杂环境中交谈时的疲劳，并通过帮助在嘈杂的教室中引导注意力来改善患有双边CI的儿童的学习结果。此外，这些实验的结果可能会影响其他听觉植入性假体的信号处理发展，如听觉中脑和脑干植入物。

 DESCRIPTION (provided by applicant): While cochlear implants have been successful in enabling speech understanding in people who have severe-to-profound hearing loss, performance in tasks such as locating the direction of a sound and speech understanding in noise remains challenging. These tasks are aided with binaural hearing in people with normal hearing, but bilateral cochlear implantation has not provided the same degree of benefit. Much of this deficit arises from the way sounds are converted into electrical stimulation in modern day cochlear implants (CIs). Modern CIs operate by dividing the incoming acoustic signal into a number of channels and encoding each channel with a constant high-rate electrical pulse train. This processing is known to affect sensitivity to interaural time differences (ITDs), a binaural cu important for sound localization and speech understanding in noisy situations. In bilateral CI users, a conundrum exists where good ITD sensitivity occurs with low rates of stimulation but better speech understanding requires high rates of stimulation. Proposed solutions typically mix rates of stimulation at different channels, where low rates are used in low frequency channels while high rates are used in high frequency channels. This approach assumes that ITDs, a dominant cue at low frequencies in normal hearing listeners, should be presented where the cochlea is most sensitive to low frequencies. However, measurements of ITD sensitivity in bilateral CI users show that this assumption may not necessarily hold true, suggesting that alternate approaches can be considered for presenting ITDs in CIs. The objective of this research is to measure the extent to which bandlimited frequency modulations (FM) encoded within a high-rate electrical pulse train can increase binaural hearing benefits in bilateral CI users. In contrast to solutions that use mixed stimulation rates, the novelty of encoding FM is that ITD cues can be presented on all channels and thereby maximize ITD sensitivity in all CI users. The goal of this work will be to demonstrate the feasibility of using FM encoding to improve the binaural hearing abilities of bilateral CI users, an outcome that has not been achievable to date. Our focus will be on determining optimal FM parameters for maximizing ITD sensitivity in bilateral CI users. Improving the binaural hearing abilities of bilateral CI users wll have a positive impact on how they interact in everyday listening situations, by decreasing fatigue when conversing in noisy environments, and improving learning outcomes in children with bilateral CIs by helping to direct attention in a noisy classroom. In addition, the results obtained from these experiments may influence signal processing developments in other auditory implantable prostheses such as auditory mid-brain and brainstem implants.