Cortical processing of informational masking

项目摘要/摘要 助听器和人工耳蜗最紧迫的问题是它们在嘈杂的环境中功能不佳。 对于大多数用户来说，在这种环境中，即使是轻微的听力损失也很难忽视背景声音。 抑制不需要的声音对于在工作场所等社交环境中的交流至关重要。无能力 在这些情况下理解言语，称为掩饰，可能会导致社会孤立和就业减少。 两种主要类型的掩蔽干扰了助听器和人工耳蜗的最佳功能。第一 这种类型被称为能量掩蔽，通过心理物理学、生理学和建模得到了很好的表征。这个 第二种类型，称为信息掩饰，目前只被定义为一种心理结构，而且更少 明白了。当目标语言和背景声音刺激相同的听神经时，就会出现能量掩蔽 纤维在同一时间。即使是一个理想的监听者，也大多无法恢复一个被能量遮盖的目标。 相反，即使当目标和背景声音在时间上不重叠并且 频率，以及理想的听众何时可以恢复目标信息。因此，信息掩码持有一个 改进助听器和人工耳蜗设计的关键。此外，个别听众在以下方面存在显著差异 他们压制信息掩饰的能力。然而，助听器和人工耳蜗术只是为了 缓解能量掩蔽，忽略信息掩蔽的脆弱性。朝着更好的装配方向发展 助听器和人工耳蜗，我们建议制定一个客观的易受信息影响的量表 基于皮层功能的掩蔽。 我们建议在人类和动物模型中研究信息掩蔽的皮层机制。 人类听觉处理的生物体，蒙古沙鼠(长爪沙鼠)首先，我们将测试 听觉正常的人类听者以及信息掩蔽条件下的沙土鼠 同时从听觉皮质进行记录。在人类身上，我们将记录血液的血液动力学反应 氧合，使用快速和稳健的评估技术，具有临床意义。在沙鼠身上，我们将测量 训练过的动物听觉皮质中的神经元活动。我们将使用这些数据来制定一个客观的衡量标准 个人对信息掩饰的脆弱性。第二，我们将研究神经机制。 通过在背景声音中引入快速不可预测的变化并评估是否高来进行信息掩蔽 信息掩蔽的漏洞是由于主要依赖抑制后台活动(AS 而不是对靶的增强反应)。第三，使用我们的动物模型，我们将测试 听力损失如何影响对信息掩蔽的敏感性。 总的来说，这项提议将从功能上定义知觉和大脑皮层的信息掩蔽 处理级别。预计这一结果将极大地促进我们对其起源和范围的理解 在有背景音的常见日常情况下，这种中枢听觉处理缺陷。

PROJECT SUMMARY / ABSTRACT The most pressing issue with hearing aids and cochlear implants is that they function poorly in noisy environments for most users, where even mild hearing loss can make it difficult to ignore background sound. Suppression of unwanted sound is crucial for communication in social settings, such as the workplace. Inability to understand speech in these situations, called masking, can lead to social isolation and reduced employment. Two principal types of masking interfere with optimal function of hearing aids and cochlear implants. The first type, called energetic masking, is well characterized through psychophysics, physiology and modeling. The second type, called informational masking, is currently only defined as a psychological construct and much less understood. Energetic masking occurs when target speech and background sound excite the same auditory nerve fibers at the same time. Even an ideal listener would be mostly unable to recover an energetically masked target. In contrast, informational masking occurs even when target and background sound do not overlap in time and frequency, and when an ideal listener could restore the target information. Informational masking thus holds a key to improved hearing aid and cochlear implant design. Moreover, individual listeners differ dramatically in their ability to suppress informational masking. However, hearing aids and cochlear implants only intend to mitigate energetic masking, ignoring vulnerability to informational masking. Towards improved fitting of hearing aids and cochlear implants, we propose to develop an objective scale of vulnerability to informational masking based on cortical function. We propose to examine cortical mechanisms of informational masking in humans and in an animal model organism of human auditory processing, the Mongolian gerbil (Meriones unguiculatus). First, we will test normal-hearing human listeners as well as gerbils under conditions of informational masking and simultaneously record from auditory cortex. In humans, we will record the hemodynamic response of blood oxygenation, using a quick and robust assessment technique with clinical relevance. In gerbils, we will measure neuronal activity in auditory cortex from trained animals. We will use this data to develop an objective metric of an individual’s vulnerability to informational masking. Second, we will examine the neuronal mechanisms of informational masking by introducing rapid unpredictable changes in background sound and assessing if high vulnerability to informational masking is due to predominant reliance on suppressing background activity (as opposed to enhanced responses to the target) in humans and gerbils. Third, using our animal model, we will test how hearing loss affects susceptibility to informational masking. Collectively, this proposal will functionally define informational masking at both perceptual and cortical processing levels. The results are expected to significantly advance our understanding of the origins and scope of this central auditory processing deficit in common everyday situations with background sound.